It probably depends on the stairs, but with our house it is pretty much impossible to get out of the house without the pup encountering stairs. We live on a hill so there are stairs going out the front door. And you have to go down a flight of stairs to get to the "potty door" (we have a small area in the back where we do the nightly potty outings). Of course both dogs are down in the lower level (walk out basement) with me at night.
So I guess what I'm saying is that until the pup goes through the first growth spurt (12-13 weeks old), we are carrying up and down the stairs. This because they aren't too steady on their feet and can take a tumble.
When they are big enough, that's when we get down on our knees and show them step by step how to go up and down the stairs.
Bertie is flying up and down the stairs effortlessly at 15 weeks old. Actually with him, the only care we take is making sure he isn't leaping from 4 steps up. Which he will DEFINITELY try to do because he's insane.
About the crate - I'd suggest keeping a crate for sleeping in your room. And then have another crate in your living space somewhere where you can pull it out and set it up to contain the pup without isolating him nonstop.
I don't crate at night (my bedroom is small enough to be a crate for both goldens), but I do have a crate stored under our living room couch for those evenings when I'm eating or cooking or whatever.
I would use a baby gate, but my daredevil pup climbs gates and leaps over the top of them.
Hence why I've totally embraced using a crate with this guy.