Im completely new to gas powered flight, i have 3 electric planes and want to get into gas. Just a few questions, i hear a lot about glow engines... and would like to know the difference (if there is one). Also besides the electronics what all do i need. I just want to make sure i know before i get into the purchasing.

Im looking at getting a trainer or some easy starter plane for the first... so relatively small and slow. what are the best engine sizes for these planes?

Thanks