Does NEX has to be on NEX wallet for staking ? Can one transfer NEX on NEO Wallet and still participate in staking ?
Nex will be locked in by smart contract. So basically if u login into neon exchange by neo wallet and stake ur nex. Your nex will be locked.
Looking at this screenshot, it seems staking will be done via the Nex suite. Definitely will be done on Nex platform and like Ashrith said, you can use your Neo wallet keys to login, access funds and stake there.