Go for it!
There are a ton of good engines. Get what fits your budget. Orion is good, Novarossi, Alpha, OS, whatever..
As for breaking them in, tuning them, running them, etc.., people here will help you out no prob. Nitro, contrary to what you have probably heard in electric circles, is not rocket science. Nor is it necessarily finicky or difficult. It's fun!
Fuel-wise, I run %25 nitro, but I think lots of people run %30. With %25 you don't have to worry as much about head shims - something I have to admit to knowing nothing about. I run %25, never mess with shims, and get on swimmingly...
If you have a local track where they race nitro truggies, maybe just go and ask.. You can do the conversion based on what you can find out here, and get everything set up. Then maybe somebody at the local track can help you out. If not, you can get all the info you need here. Go for it!