If all you have on hand is a whey protein then adding milk to it will slow the absorbtion. The only time you really need to get protein in your body fast is PWO. If you can spare the extra cash buy a casein protein for bed time or in between meals. I"ve used Micellar Matrix before and really liked it and its not that expensive.

The whole point of weight gainers is to add extra calories to your already solid diet. It's quick and easy calories.

So yeah about 2 hours after a meal you can drink this.

How many calories are these meals?

You could drink like half a serving along with these meals if you want.

That looks fine.

Also how many calories do you want to eat a day? If you find it hard to meet 4000 or 4500 calories a day (or however many calories you're trying to eat a day) from real food then that's where the shakes come into play.

If you have no problem reaching your goal in real food then you may not even need the weight gainer.