As someone who is currently involved in the development of a 135 cert, here's my 2 cents.
Jeff foxworthy (I think) once said that getting married so that you can have sex is like buying a 747 so you can get free peanuts.
Starting a 135 op to get a flying job is like building a homebuilt from scratch so that you can get your private ticket.
You gotta really want to be in the 135 biz.
The paperwork is immense. As an earlier post mentioned, it took 5 months for a cert that allows one pilot and one airplane. And that was usung an ex-fed to do a lot of the legwork. My guess is since the aircraft is single engline that it's a VFR only op?
Now if you want 2 or three twins to do IFR? Not going anywhere for a while? Have a couple hundred snickers bars.
Unless you can get regular work hauling freight, you then have to go out and sell your services in the cutthroat pax-carrying industry.
The insurance companies are making harder than ever, as was also noted.
If it is what you (or your friend) really wants to do, then you will probably succeed.
BTW: You can go to your local FSDO and watch a video on the process.
Also check out FAA.gov, and hunt around for the 135 homepage.
Good luck! I know we'll need it.