Hey thanks for being interested :)
Both player and enemies are based on a so called Character class. It is mainly used to deal with stats, collision etc.
AI behavior and player input are handled via AI_Controller and Player_Controller respectively.
Meaning when and how an enemy attacks is decided by the AI_Controller right now and it only handles melee attacks. You can add ranged attacks by enhancing AI_Controller and the Character (or Character_Stats) classes. Just depends on how exactly you want to do this.
For example it's kinda important whether you want to have hitscan, bullet objects or both as ranged attacks. With exploding enemies the same question applies. Everything is possible, but you'll have to implement it. Hitscan should be the easiest to implement without having to write too much code.
Also the template only provides the main game scene, no main menu etc.
Hope this answers your questions. Have a nice week :)