1) How are last chancers "one shot weapons"?
Last chancers are a:26 points per melta/plasma/sniper. 11+5(specialist)+10(melta). Presuming for a moment that they don't die a screaming death deepstriking they're S/T 3 and suddenly high priority targets with no armor. They devour points hungrily, and don't have the staying power they need to have when they start out at a minimum of 165 points for 6 models. (210 for 4 specialists with melta/demo/sniper/plasma) 165 points is 5 points more (until May) than 25 lasguns in 3 scoring units.
2)How is carapace useless if there is no cover around and I'm against
SM, with Ap5 weapons.
Carapace armor is +20 points per unit. That cost begins to stack up with platoons of 5 squads - it quickly could pay for another infantry platoon. If you've got no cover saves against
SM armies you still should be outshooting them. A fire support squad attached to the
HQ would be very useful here. (There's a theme here

) Engaging guard across an open field should be tantamount to death.
3)I have NO heavy platoons they're only attached to my squads and the rules say that any unit with 1(one) BS3 model may take it and it doesn't apply only to; Plasma, Meltas, and Sniper weapons.
that same 10 points could give a +1 cover save, or be saved for use elsewhere.
4)Why shouldn't I want to infiltrate a chimera with 6 shots?
You *WANT* to, but read Infiltrate again: "If a unit with this ability is deployed inside a transport vehicle, it cannot infiltrate." Stealthy is not an adjective that should be applied to a Chimera.
5)I don't roll average rolls and I would rather keep half a squad at half victory points than give the enemy full victory points.
Dave47 has this cold.
6)
IG infantry suck and aren't near my tank to give it support.
If you're using guard for melee - you're using them wrong. A Leman Russ can fire either its ordinance, or trade 9 S5 shots for 1 S9 shot. A guard Lascannon might be 25 points, but if the squad isn't moving its no trouble. Also, the
HQ platoon should have a the full compliment of lascannons you need.
7)Said I was taking honorifica off and I want the power weapons.
Why? So the WS3 guardsman can maybe deliver a S3 power weapon while the rest of the squad dies horribly. Or you can pay for a melta gun. That dreaded S3 AP5 Hellgun isn't impressing anyone, and storm troopers can be bought in 5 man teams leaving points for lascannons in your
HQ platoon.
8) The purpose of the Stormtroopers is that they can move and shoot, I see there's an extra assault weapon, but Stormtroopers have 4+ armor and I would be wasting points on a lascannon for them.
The point here is to illustrate possibilities. The Veterans doctrine allows you to use hardened veterans in the same numbers, who are cheaper, deliver more firepower, and are effectively the same with the deep strike doctrine.
9)I only play normal games and I can't get the executioner yet, the heavy flamers is a decent idea if I was against a horde army.
Its available in the Imperial Armour books as well as Apocalypse...and confirmed in the may
IG codex release.
10) I was asking if it could be applied against Tau, I mean, it would help against said "superior"
HTH units, but orks at a lower initiative as are most Tyranids. Both of those often end up in
HTH combat so it is impossible to avoid.
But it doesn't help against Orks - you're climbing up against
WS/T 4. Tyranids need no mention. Tau should not have a melee unit. You should laugh at a tau with melee troops.
Demo charges are a waste of points precisely because they are one shot weapons.They're not worth 25 points to field (for Last Chancers) especially with the inherent lack of accuracy in a blast weapon now. Guardsman throws at a target 1.001 inches away, has a 1 in 3 chance of landing on target and an average scatter of 3 inches. Not that you want to throw it so short. Using a special weapon squad should be as vehicle or
hq hunters. Same deep strike, same S8, and
IMHO more reliable.