yea, i buy those things by the dozen
as to how many troops you get, if it is launched you get what it has onboard at the time. if on planet it gets up to half the planet pop, but obviously not more than it can carry. i use it to a) stock up for wars ,
deplete their populations (thereby slowing their growth), c) slow their expansion, d) fill my planets. i sometimes even give away imp troop carrier tech to improve my investment
for those that think the ai has no personality, try this technique and you may change your mind. torians for instance make TONS of transports. more than their racial growth bonus can account for even. and they build slow ones at that. drengin, yor, terran, and those bug guys whos name i forget make fast transports, but in more modest numbers. this holds true even if they have the engine tech to build better. some just dont bother to make them fast, ever.
there are some things you have to remember if you do a lot of this tho. bought transports will start out in their territory, which cause problems with your relationships til you get it well away from them. and for every other faction whos territory you pass thru. lots of transports on you own planets even cause friction for you immediate neighbors. for instance, i am constantly being attacked by minor races
seems they get upset by the parade of mercs passing near their territory. growing your planets with mercs can cause morale problems if you are not careful. those mercs in their territory also degrade your ability to trade with that culture as long as they are close enough to be a threat (diplomatic trade, not merchant trade).
the technique is pretty powerful, but it does have it's faults. but just being able to conquer them with their own ppl make it worth the trouble
