If they found out that you are a botter. Yes. If they just take u down for weird activity it will probably only be a suspension
Currently no. If they scanned your computer (which they are able to do) they would find it within seconds. But it is not legal in most countries coz of privacy issues. Nobody but Blizzard actually know what/how they attempt to detect botters, though there are theories (which I will not talk of here). There are many ways to link your individual computer/hardware, most notably MAC and IP. This coupled with payment (credit card name) and all the other abusive uses (ie 24/7 farming in one zone, spamming /2 WTS gold, excessive ah posts, etc.). There is no sure way to "not get caught". But there are many precautions you can take. If you bot smart, you will be fine. Don't (!!!!EVER!!!!) bot an account you need to keep. Its a game of cat and mouse, sooner or later the cat will get the mouse. If you plan to use it on an account that you care a lot about. Only bot whilst you are infront of the computer and able to intervene if needed (answer messages etc.). Even using this method, if there is a software detection your account will be lost (see above)
If you get caught breaking blizz's rule 100% ban, no questions asked. If there is some ambiguity as to whether you were cheating or not. It is up to you to convince them otherwise. Normally since the game is designed for kids a weak excuse will get you out of trouble first time round. (no promise from me though)
Nope, read again. Some people bot years and do not get caught, other bot 2 hours and are perma banned.
In my view, what distinguishes people who get perma banned so quickly and those who bot years without getting caught is as simple as a matter of greed. If you are greedy when botting, pushing safety boundaries further, etc... that will get you in trouble. But if you bot as if you were doing a recreational hobby, its much safer. Personal experience