I'd rest at least 3 days a week, it's really dependent on all the other factors you mentioned too. As for what to eat there's plenty of topics on this do a search. At least 8 for sleep, I've found personally that when I do cardio only 2x a week and not very intense cardio is when my strength goes through the roof. Any time I wanted to go for pure strength I'd do 3x3s, though it doesn't do a lot for endurance or for muscle size. I'm sure other people will chime in here.