You've got the basics of a very nice list here, I've been playing T'au since 5th, so I feel I can provide you with sufficient advice
Firstly, the two broadsides, change them to have the
HYMP instead of the Rail Rifle, this is because the slightly lower strength trade trade off for four more shots is just mathematically better and much more advantageous against vehicles and
MCs. Also, give them Velocity Trackers rather than Drone Controller, the ability to swat nearly anything out of the skies at will is beautiful, especially against those pesky Skyhammer's used by
SM players. You should keep the marker drones, as broadsides are so devastating with
ML support. (2 x 118pts(236pts))
Secondly, I'd do four squads of
FW all with BKR and made up of 4 normal and 1 Shas'ui (again with markerlight and target lock) the smaller squads make them more vulnerable, but the BKR helps with morale, plus, the smaller squads allow more objectives to be captured, as well as, you can divide your firepower much more effectively. (4 x 75pts(300pts))
Next, the Ghostkeel, I agree with taking the Fusion Collider, but, take the
TL Fusion Blaster and also for the signature systems, i'd take the
EWO and Velocity Tracker so you can melt vehicles, flyers and anything coming from Reserves. (166pts)
I agree with the Ethereal entirely, but, remember not to put him with any of the squads as wounds can be carried over onto him, also, try to keep one
FW model from each squad within 12" of the ethereal and then the unit will benefit from the special rule you choose. More importantly, it's just not worth putting any points into him for upgrades. (50pts)
Lastly, for the Crisis Suits, don't spend points upgrading one to a Shas'vre as it's pointless for just +1 leadership, so I did the suits loadout as 3 x Crisis Shas'ui, all with 2 x Fusion Blasters (mathematically, 2 shots is better than one twin-linked) and they also all have a target lock as two Fusion Blasters is usually enough to get rid of a rhino, or even two for a Land Raider. (3 x 58pts(174pts))
Overall, this means you have 926pts, so i'd put 6 marker drones into the crisis suits units bringing it upto 998pts!