Dark Riku wrote:I summon forth Forest Radio!
(He better shows up! Or else...!)

Ok, so GK t3 is actually pretty straight forward (I'm speaking of 3v3 perspective here since that's what you asked about). It works like this:
Do you have sufficient anti-vehicle?
If yes, get terminators first. Then paladins.
If no, get paladins, then put terminators on overwatch.
A quick note about your terminator variants ranged capabilities:
The incinerator sidearm is a very cheap upgrade (for a late game unit anyways, compared to nobz/loyalist/chaos terminator upgrades it costs almost nothing) and pretty much makes them impossible to kite by light infantry units, it does absolutely INSANE burst AoE damage. In fact I consider it so overpowered that I actually don't buy it, but that's another story
The psycannon is also pretty cheap and is great at chasing tanks and finishing them off on rear armor. Don't forget to use the mind blades global on your terminators to increase both their ranged and melee capabilities: judicious use of mind blades can make the difference between a living and dead vehicle, or a won and lost melee brawl.
You also might want to purchase a terminator librarian in t3 after your first terminator/paladin variant, he does an excellent job of supplementing them. Don't be afraid to experiment with him.
The Land Raider Crusader is like other Land Raider variants, park it on a VP with some support and have it shoot the shit out of anything that comes hear while ur IST repair it. It suppresses pretty quickly so it's pretty much unapproachable by any sort of melee unit unless it's assault terminators, enemy paladins, or supa tuff beam nobz. It costs red but also can be dropped anywhere, any time you have sufficient red and resources, so don't hesitate to help your allies out.
I'll try to look at the replay soon.
EDIT: Ok I looked through the replay, I think the big main mistake you made was floating so much req in the beginning of the game, you went with a light build which is fine in team games, but easily could have added another IST squad. Don't hesitate to build lots of generators either for your team when you have so much requisition.
Everything else I think will come with some more experience, just keep playing and practicing and trying things out and you'll get a feel for what to do
