Shoestringracer:

If you want to go gas and I recommend gas for this plane. (read post #1226) There are a host of engines that will fit the bill.

You have a wide range of choices like the BME 50, ZDZ 50, DA 50, Brison 3.2 and the 3W-50. All are good power plants for this plane and in their own right well designed and manufactured. The other engines are OK but I prefer the lighter, more (I think) reliable engines with electronic ignitions.

I'm using the BME 50 and ran it out of the box with not a single problem. Flys the plane with plenty of power to spare.

I guess all the engines in this class would work just fine. It just comes down to availability and personal preference. I don't mention price because they are all priced within a couple of dollars of each other.

Yes, it will take longer than 15 hours to get this plane into flying condition.

I can't answer your last question because I personally do not know your level of skill and maturity. If you have to ask the question of strangers on whether or not you are ready for this plane, I would have to guess NO.