1: thats depends 🙂
2: sure, there are plenty kits on a budget. I have used a $250 for years, only the kick mic was total rubbish. Actually so bad I took it back to store and said, this must be broken. Got a new but it was as bad as the first:D
3: absolutely, try it. check this http://blog.shure.com/faq-whats-the-difference-between-the-sm58-and-the-sm57/ shures own words. I would try out the akg d112 mkII as a kick mic.
4: I would get a kick mic first. Probably som tom mics next. Next thing would be stereoizing the overheads... I would go for a couple of sdc. Option would be a second ldc, the same for conventional stereo ovead micing. What talks against that would be.. would you really want to buy a second at2020? another option would be to get another ldc with figure 8 and use a mid side mic configuration. This is the main point why to first get a mic with figure 8 then upgrade with a better cardiod only ldc. You probably want to use your new fancy mic for the mid part and your first cheapy mic for side.