1) you can, for example ide-cable having two sockets, one for harddrive, one for cd-rom
2) Towers are a bit costy for A1200, but I recommend Ateo tower. I don't know if its on sale anymore, but the tower is great, and so is the keyboard adapter. Infinitiv suck smelly ass, dont go for the lego-towers.
3) see answer one
A1200 has 2.5" cable socket, so you need a correct type of ide-cable