Is lower berth the first sold?

Hi- I am looking to traveling Toronto > Vancouver in mid-March. I know it is off-season, so less likely to be full, so wanted to understand the arrangements re: berths.

Solo travel, but I can really only afford the berths, not single cabins. I am not a great sleeper, so a bad roomate, and I don't really relish the idea of facing a stranger the whole way (I would think the seats would face the window instead; am I misreading that?)

So I have a couple questions i haven't seen answered recently here:

• The only berths currently for sale are lower berths. Are those the first to sell, meaning that as of right now I won't have company? (I understand a lot can change before March)
• Has anyone done this trip in mid-March? Is it less busy?
• Are there plenty of other places to hang out instead of facing your bunkmate for hours on end? Do they let you post up in common spaces for a long time or move you along (if not too busy, of course)?

Thanks!!