No worries, youve made me want to reinstall it. Its got quite a steap learning curve btw.
I mean youll only be using like 4-8 units a time really depending on how many palyers thre are. But the level of micromanagement is quite intence but thast whats rewarding.
Learning the basics will take you an hour probably, learning to beat your oponents without having an advantage will take significantly longer.
A tip (may be affected by patchs now) when you get the game, DONT go support. You think its the easy one to learn, far from it. You need to keep your team alive, you need to micro a repair tank following armour but staying behind and not gettign in their way. You need to micro anti air possibly in 2 plays at once to stay with 2 fast moving armys most likely. A big tip if you do paly support, dont buy artilerly. All "noobs" do it and its genearly useless in comparison to the anti air you could have bought. (might i point out i also bought artilery). Fun to play with though
Infantry in my eyes is one of the funnest classes and is effective against almost all enermy vicheals one way or another (artilery can really ruin your day though, which is good when 1 suport guy just gets 1 artiry unit to supress a good infantry guy). Very versitle. The only class in the game that can stealth (in woods). Snipers can wreck havolk. Ambushes will give you a real buz when you take out 4/5 tanks who never saw it coming.
Also you can attack choppers as infantry in woods, they will have a very hard time hitting you and you can kill them easily.
Infantry are very powerful, problem is tehy take a while to move and capping points are extreamly vunrible. Also beware, the tactical powers are very effective against you and dont cost a lot.
Best class to laern with is probably armour. Air is fun also, a tip for killing infantry is to attack ground and fire your rockets at the clump.
Mayeb if you get it ill join you and make it 3v3

But ive not played in so long you can consider me nwe to the game again lol.