First off, I only recently got this game but I must say; I LOVE it.

Firstly; what's the best weapon? Why are dual pistols 3000$ when a Thompson is 2000? Are the dual pistols better?
Secondly, is it cheaper to kill/bomb a business or whatever and buy the free site than just outright buying it?
I may post more questions here later.

The Thompson work best for me. I would suggest not arming any hood that you do not want to get in a fight. Unarmed hoods are more likely to complete mission.

I normal bomb business, I think if you only kill them the keep the business but no one is running it
Buy unless it’s owned by another gang. I never had someone not sell to me.

I would look online for a guide, some illegal business work better with different store fronts, like a speak easy behind a milk bar

Hello WalrusW1ns,

If you really love this game!
You should buy the 2 guide that are made for this game, you will learn alot from them!
The guide from Johnny Morrisey you can find on Ebay for cheap, but the guide from Michael Knight (Prima's official guide) will be much more expensive.
Also do not forget to check the manual of the game ;)
I really hopes this helps you out!

Greetings from the Netherlands.