Monetizing Advice


I’m almost ready to launch a puzzle game where the user have a number of lifes that regenerate with time. I need your experience advice about to monetize this game.

First of all, I have IAP’s just to try to boost the earnings.

After that, I will have interestial ads after X levels, not sure if admob or chartboost, but maybe in the first time I’ll try admob.
I have the option to users see a video and see their lifes refilled.
Also to boost my ratings I have a rate button that shows every X levels.

With that info, I would like to know your suggestions and expertise advices:
1 - What should be the time interval to show ads. Be aware the levels would be about 1 or 2 minutes max. Showing interestials every 3 levels should be good? Or should I change it to 5 for example?
2 - Should I ativate the option to see a video and refill lifes in the beggining or should I wait for some special time to ativate it? For example in December, like a Christmas present, I activate that option and try to boost my earnings and then in January I’ll deativate it again.
3 - About the rate button, I’m thinking in show it after each 7 levels. It’s good that way?

I’m waiting for your suggestions and advices. Thanks.