I wax mine but don't scrape it before storing it. Over the summer the wax seems to dry out and in the fall there's not much left to scrape off. I believe that this keeps the base from drying out. Some say this is b.s but it's easy to do.
I store my boards standing up on their tail and don't stack them on each other. I don't think it matters how you store the board e.g standing up/lying down as long as you don't have weight on them.
As for how often to wax, sintered bases start to get dry/white at the edges as the wax wears away, that's how you can see when wax is needed. Depending on the snow texture you may need to wax every day or two or you may only need to wax after quite a few sessions. Some say waxing is bullshit and you don't need it but I'm sure it gives you some extra glide in the flats and I hate skating.