Wallet and Withdrawal Questions - noobish

Couple of questions on wallets and withdrawals

If I get a hardware wallet, say, nano ledger, do I need to sync it first and then keep updating as I keep adding more currency/tokens? Not exactly sure how the wallet thing works (i know the very basics)

Is it ok to keep multiple currencies/tokens on the same wallet or should there be one wallet per c/t

when withdrawing back in to fiat I am assuming bitcoin is the only possibility right now?

Any links to good explanation videos about the concept of wallets is much appreciated