A good place to start would be
www.evilsizor.com.
They can take care of all your authority needs.
Progressive is good for new drivers. Depending on your driving record they will insure your entire rig, truck and trailer, even if rented or leased.
If your going to rent or lease to start, I would recommend Penske or Ryder rentals. Penske looks to be a little less expensive than Ryder.
As far as getting work and loads to run, the load boards seem to have PLENTY of work to go round. In particular "www.getloaded.com".(123loadboard.com is good too)
It seems to me that for starters, youll need at least $10,000 to get you buy until those checks start to come in.
This is what I plan to do eventually, though owning my own truck. But I will probably have to work for someone for a bit first to afford it. Otherwise I would just jump in and go out under your own authority. Youll get the experience as you go. Others here may not think this is a good idea, but I can see many have done it.
Good luck.