1) Whether you open a weak 2 or not depends on your style. With 1 partner we regularly open weak 2s with 5+cards but we have the methods to find out if partner has 5 or 6 cards, shortness etc. Playing with anyone else I would pass in a flash. 3) 3♣ is really poor IMO, you have the spades so its unlikely you want to defend. And if they play in hearts, you want a diamond lead not ♣