When you advance the timing, higher octane fights the detenation, yes you can run reg. fuel, it may or may not damage anything and same goes with power increase.
Diesels are another breed, you cant compare a diesel to a gas motor. But when you get into programmers like the hypertech, they are specifically done for each car/motor, the jet that he linked too is used for a list of multiple manufactures, there is no fuel mapping done to compensate for the advanced timing, which in turn, you should run premium fuel.
As far as programmers for the E, kpro 06 and under is your only one, unless you get into a fic, then your talking a ton of money.
Hope that helped a little.
Oh, this is about the same as doing the resistor mod that has a post up right now. Read that, it will help you understand.k