Regarding staking
do we need to keep wallet open for coins to stake or we can close it like neo wallet
also i am planning to buy VPS for staking.. is it secure to store coins on vps?
Yes you have to leave it opened 24/7. If you are willing to stake in a vps, make sure you are renting from a great vps enterprise.
Remember that we are 10% per year.
My understanding is that you can close it whenever you want, you just won't accrue more staking weight and thus not optimizing your chances of getting the full 10%