As long as all info to access your account in MEW is safe (Keystore file, Private Key, Mnemonic Phrase etc.), your balance is safe as well. There are several phishing sites popping up lately so always double check the URL before unlocking your wallet.
Yes, this is what i actually wanted to know as well with the ledger nano s. Cause i need to store all my tokens as well. So all tokens that can be stored in MEW can be stored in the ledger nano as well? Tx.
As MEW supports Ledger Nano S, you can send/receive all Tokens listed there using the device. This is a good read on
How to use MyEtherWallet with Ledger