I can only speak for the Tau half of this army, but I'll do my best to give you some understandable pointers rather than simply telling you to do things without explaining why they work (lots of people used to do that to me and I was just like .....why)
First of all, let's take a look at your
HQ. You've put together a team that has vastly different ranges within it. If you wanted to markerlight something from a safe distance, your burst cannon suit and fusion suit are very likely to be out of range and unable to actually do anything, as well as possibly your commander. As Epartalis mentioned, their isn't any point in taking bodyguards because they're more expensive than regular suits and do virtually the same thing, you could just attach the commander to a normal unit.
If you want to run your commander as a marker unit, he definitely needs a drone controller (to give the drones his BS5) and he would be best equipped with 2 missile pods, because they are the same range as the drones meaning the unit will always get to fire all shots.
Also, facing off against marines etc that have str8 weapons, they can insta-kill your commander if he doesn't have iridium armour - I always give my commander this upgrade.
As a side note for all suits, it's a lot more effective to take two of a weapon than a single twin-linked weapon.
I actually never run my commander as a marker unit, I give him iridium armour, drone controller, 2xgun drones (gives you another 4 twin-linked BS5 shots), cyclic ion blaster and plasma rifle. This makes him a pretty good trolling unit as he has a 2+ save and +1 toughness with enough firepower to nicely reduce any type of unit.
Okay, onto your troops selection - as long as you keep one team in the fish and never disembark them, that team should survive as being a nice objective secured devilfish. However, you do need to change what your fish is kitted out with if you want it to be survivable. Disruption pods are an autotake option if you're using the unit like this as it maximises chance of survival. You've done well with putting the
SMS on - this allows the fish to sit out of line of sight on an objective (if the terrain allows this) and just shoot at whatever you want in range, ignoring any enemy cover, perfect.
The other 6 man team will get slaughtered if not placed well though. Ideally, they should be sitting in cover holding an objective at the back of the board, but simply having them in cover will do. Their long range allows them to be a bit of a nuisance for enemy troop units and also light vehicles.
Elites and Fast attack: you've made a grave mistake here in that you haven't used any crisis suits. They are the best component of your army and are very versatile. I'd take these over stealth suits anyday. First of all, get rid of the drone squadron, they're virtually useless like this. That's 84 points you're paying for a unit that only averages 1 markerlight hit per turn - a unit of pathfinders with no upgrades would be much better at this job. And you desperately need pathfinders in your army, especially to boost riptide
BS. I'd possibly even stick two units of 4 pathfinders in this slot for 88 points.
Okay, that stealth suit unit is hugely expensive for a unit that isn't particularly effective. My suggestion is get rid of that whole unit, and replace it with a crisis team. Now, the loadout of the team heavily depends on the enemy you think you'll be facing. If you'll be facing a lot of heavy armour, you'll want suits with two fusions each (if you can afford 3 suits, you give 2 of them a target lock so they can basically deep strike and blow up potentially 3 vehicles before they receive any return fire - bit of a suicide unit but works great).
If you'll be facing many Terminators (or equivalent), you'll want to have a team of suits with two plasmas each - the AP2 denies termie armour saves, and at rapid fire range, that's 12 AP2 shots you'll be firing (averaging 6 hits, 5 wounds = lots of dead termies). Plasma is also great for wiping out normal marines for the same reason, as well as character units, and
MCs. They can also hurt armour if they've already fulfilled their primary role in a game.
If there's a tonne of light armour on the board, missile pods are perfect. 4 Str7 shots from each suits can glance to death or blow up 2-3 vehicles per turn. Long range (36") makes them very versatile as they'll always have a target.
If you're dealing with hordes, burst cannons and flamers are the best options here. Imagine a whole unit of Tyranid gaunts being obliterated by 24 burst cannon shots, or 12 combined with 3 flamer templates - ouch! Flamers are also great charge deterrents because they auto-hit in overwatch due to them being templates. This is incredibly useful when facing choppy enemies and gives your suits better survivability. If you're struggling to find what to spend your last 5 points on, sticking a flamer on one of your suits is a good way to go. They can go about their main role of tank-popping/heavy infantry hunting and then protect themselves from assault by pesky weaker units.
The other main strength of crisis teams is that they can jump-shoot-jump (
JSJ). This allows them to move out from cover, let off some shots, then hop back into cover with their thrust move to weather any return fire in the enemy turn.
Onto your riptide: riptides are great, full stop. He's a very durable unit. You don't need all that stuff on him though. Stimms are enough to keep him alive, he doesn't need a shield generator too. And the missile drones are expensive - I'd say drop these and spend that 50 points elsewhere in your army. An
EWO is a great upgrade for the riptide - he is usually a big target and you could run into a lot of trouble with a player who drop pods a sternguard squad right next to him.
EWO (used at the end of THEIR movement phase) means he could actually wipe the whold squad out with an ion accelerator blast before they do anything at all. You won't be able to use the
IA next turn, but you still have your secondary weapon. The secondary weapon you pick depends on your situation really, but I usually pick
SMS for that line of sight/cover-ignoring long ranged goodness. The accelerator is mostly what I go for due to its higher strength, but if you're facing lots of flyers, the burst cannon is better at bringing them down.
As a side note, if you're facing a flyer-heavy list, take
EWO with velocity tracker on a burst cannon riptide, with fusion as a secondary and watch your opponent cry as his flyers drop out the sky.
Heavy support: broadsides are great, but only if you take them
HYMP with
SMS. This is the way to maximise their killing ability whilst also making them pretty good at taking down flyers (4 twin-linked str7 shots? Flyers will cry, light ground tanks will cry even more). You don't need any extras on them, just take the single 65pt broadside. If you can fit it in, take another single broadside with the same loadout as a separate unit (you could take them in the same unit if you wish, but you'd need to give one of them a target lock so they can fire at a different unit).
I'll just give you a breakdown of other cheaper
HQ options too:
Cadre fireblade - absolutely awesome if you attach him to a 12 man fire warrior team. This allows you to spit out 24 str5 shots at 30" (or 36 at 15") whilst also allowing you to fire his BS5 markerlight at a different unit using split-fire. Combine this tactic with pathfinder markerlighting for maximum effectiveness/making your opponents troops disintegrate.
Ethereal - in short, he's pretty amazing for the points cost. Buy an aegis defence line, stick 2 full squads of fire warriors behind it and dare your opponent to try and engage your squishy tau in close combat. If he tries, he'll never get there alive, and the
FWs benefit from the ethereal's LD10.
Another thing - I've had huge success with the railgun hammerhead. Put Longstrike in it and you have a str10 ap1 gun that hits on a 2 and has unlimited overwatch with it's secondary weapons. Great for popping open a land raider turn 1 and forcing your opponent to try and deal with this threat whilst leaving the rest of your army to do its thing (if they can get in range first). The only thing is, the hammerhead is a pretty weak option without Longstrike, so you're best using fusion suits to kill av13 and 14.
Hope some of this helps