1. if you are planning on carrying, i dont understand why you would want to cut corners on something that you would want to trust your life with. personally i dont know many handguns under 250. and i would save up a bit more for a tried and true carry piece.
2. get a caliber you are comfortable shooting with, round size and stopping power has nothing when compared to shot placement. 3 well placed 9mm JHP's to the chest is going to bring down a bad guy just as well as 3 well placed .45 JHP's to the chest, and if you cant hit the target with .45, dont get .45
3. 3? day waiting period, background check. pretty much it. just get your CPL first. makes the buying process easier.