Wanting to do a few hauls....need some answers

This is for you guys who do this alot, hopefully you can help. I want to use my truck and horse trailer on my days off to make some extra money.
I only want to haul in my state (Virginia) and maybe some adjoining states. I only have a two horse gooseneck so weren't not talking a lot of wieght, but what kind of insurance do I need and what companies do you guys use for that?

And what DOT or other fed. authorities do I need to have and how do you do that?

Thanks.