First off welcome to the hobby
Pros of 2 and 4 stroke engine:
2 Stroke- Faster, easier for a beginner, cheaper, lighter.
4 Stroke- Better fuel effieciency, low nose (no big muffler), better acceleration.
Theres more but i cant think of them right now.
Both types of engines can be used on almost any glow plane. However sport, aerobatic, and trainers in my opinion should use 2 strokes. (This is because they have a better weight to power ratio). 4 Strokes can be used in scale planes because they have a low noise level and they dont have a muffler sticking out.
I suggest you get a 2 stroke at least for your first two planes (your trainer and usually a sport plane). Then if you want a scale plane and are willing to spend the extra cash you can get a 4 stroke. 4 strokes also are harder to set on the needle valve but if you have an instructor he can do it for you.
Remember that if you get a 4 stroke you need a bigger engine than if you were to get a 2 stroke.
Hope this helps,

Papa