Well, if you don't have any experience w/ the zoom game I'd recommend you to start playing 1 or 2 tables at most in order to know more about the dynamics of zoom.
You should focus more on improving you game than playing actually, i.e. no matter the number of hands you play in micro stakes, what really matters is how often you study, your winrate and focusing on being prepared for higher stakes.

Cheers.

I actually don't hate if you start with 3-4 tables and push it hard, that way you will improve too if won't play autopilot and c-game poker. But you gotta have bankroll and be mentally strong for swings and pressure of making tough decisions in short time

Max 2 tables and sitout on other when you have big hand.
Session lenght is totally dependant on you, try to be aware of your concentration (set alarm every 10 min and check).
Planning should help.
Study:play ratio imo should be like this: take a topic, let's say BB vs BTN preflop ranges (cold call and 3bet). Prepare material on side. Grind until it's automatic (unconcious). Take a new topic.