Good questions! First of all, welcome to OCDO! You'll learn a lot as to what's mandated, where not to carry, what's required, etc, just by going through the "Where Did You Carry Today..." thread. About 90% of your questions can be answered regarding where it's best and where it's not. As to what firearm you choose to carry? That's entirely up to you. Carry the one that's going to do the job if and when you'll need it.