Glow plug life depends on the quality of the plug you are using, fuel, ambient temps, tuning, and stuff like that. Generally I'd say I replace 1-2, maybe 3 per season (in rare instances) in an engine depending on the particular engine and how much it gets flown.

Flight times again depend on the engine, fuel tank size and the type of flying. Figure anywhere from 10-20 minutes. I personally like 10 minute flights and landing with a little fuel on board as a safety margin.

If you are still considering electrics, this looks like a good one for a first plane: http://e-fliterc.com/Products/Defaul...ProdID=EFL2725

I'll admit I haven't flown it but I've seen it and it looks very nice.