i researched my start up for 8 months before taking the plunge, and oh boy what a plunge it was.
every question you ask about this business may aswell be "how long is a piece of string,
for instance, how long does it take to clean a room, depends on soilage, stains equipment used, amount of furniture etc....
you just need to get as much information as you can get, do some traing, if you have the money do lots of training, going to the training events is the best thing you can do, not only do you learn how to clean safely but you meet a lot of carpet cleaners, newbies and veterans, talking to them is worth the training fee alone.
like steve.
trawl the back posts on this forum, theres lots of varied answers on here, so take it all in, evaluate and then make your decision.
check out you opposition and see what you can do that makes you more appealing than them, dont base your new start up on cheaper than the rest, cheap is good but not the b all.
good luck and i hope this helps a little.
derek