When I read your first answers and afterwards your recomendations, I see you know what you're talking about, especialy when you say " However most of them were really unfinished" and recommend " FINISH them. It's really easy to abandon projects and to start over and over again. It's really hard to finish them." xD
Anyway thanks for all these answers. Well I'll try to implement A* pathfinding in my game maker project, and other before starting with unity.