Crackdown questions.

Read the FaQ and didn't see the answers I was looking for. Most of these are achievement related.

1. Are there still gang members around after you finish off all 3 kingpins(21 bosses)?  I have one left and I wanna level up my shooting and driving by killing some gang members.  

2. After you kill, all 3 bosses is the game over?  Can you start a new game with your super powered agent?

3. Is your leveling up tied to the character or your campeign?  When loading a campiagn can you switch to another character and will he carry on the leveling skills?  

4. It seems like the roof top races would be easier when all the bosses are dead.  IS this the case?

Thanks!

you can still turn on gang members after you kill each boss. not so sure about bringing your character over to start a new game, i hope so. i am pretty sure you could use a new character skin and keep your stats. and yes rooftop races are really hard when the bosses are not dead yet. but it is also fun trying to jump 30 feet in the air without getting hit by a rocket