Of course strength potential is higher in 200's than in high 160's. But as a beginner you should be able to maintain your strength and possibly even increase it.
It won't likely be *pure muscle*. But you can gain that much weight without looking fatter (or so). And without having negative effects on performance.
If you eat bigger meals you don't waste calories from them. They just take more time to digest. Normal mixed meal hasn't digested even at the 5 hour mark. With higher protein content it will...
No, it wouldn't be optimal if aerobic exercise is strenous. Aerobic exercise will hinder anabolic genes. And stimulate AMPK which will hinder protein synthesis.
It depends. Start a little lighter and work your way up. You can increase volume, intensity or add new exercises. Experiment what works/feels best. Little variety every now and then doesn't hurt.
b) Dairy contains a lot of calcium which can hinder the digestion of magnesiumd and zinc. But that will only happen in high doses, so there's no need to...