Eshop have January sale right now until 25/01

Some1 inform me that for region registration better use Canada - Alberta, bc won't have tax and also more games in eshop. But I buy the Dragon Quest VIII digital still got C$2.50 for the tax.

Is it true that we should avoid register Malaysia as our region since there are not many games in its eshop?

By the way, I have 2 console, can combine 1 account for both account? Or have to be separate?

For digital games, if we format/change the memory card can we still obtain the games that we bought in eshop?

Thank for the pencerahan