Your first two sound like you want to be in zone 2 a lot. It's boring for most people (I actually like it) but it does increase endurance and burn fat more effectively (i.e. more of your energy comes from fat than at more strenous levels and you can keep it up longer. Full on sprints do burn more fat than zone 2 but you can't keep them up). I use Joe Friel's definitions for the zones but basically any of them will get you in the ball park for zone 2.