I'm using pro complex right now but not the gainer. It's pretty expensive but i must say that the taste is not that bad for strawberry flavour, assuming that chocolate tastes better. My friend is using pro complex gainer, he said vanilla taste is nice and it's not as thick as serious mass.

Depends, its better to take hydrobuilder if youre skinny. Hydrowhey if its harder for you to diet. You can take hydrobuilder if you're overweight, but it'll double your work when you want to cut. So hydrobuilder for bulk, hydrowhey for cut. But in my opinion, Pro complex all the way.

it's not wrong but it'll be harder in my opinion. calculate your calories deficit, work on your diet and it'll be a lot easier.

Actually it depends on you. If you're good at diet, then it should be alright.