Youtube Channel Promotion

Sure, as long as you don't require anything of the entrants.

Sure, as long as we don't have to like anything or join stuff you are good.

I'd say yes, as long as you don't post referrals or ask users to "perform any special action in order for their entry to be considered valid, such as liking a Facebook page, or following a Twitter account" because those are against the rules.

Edit: Ninja'd :D

Think nothing wrong with that while people can put their steam groups, greenlight stuff etc. but as long as you don't require something like subscribe or like something as they said.