Do we have to update to the new wallet if we just plan on holding? I have the wallet.dat file for the old wallet and my private keys - is it necessary to download the new wallet?
Hello. Yes, we recommend to update the wallet to the latest version and to re-sync the blockchain.
But if you are for a long hold, and if you are not planning to use the wallet often, it's up to you really. Wallet.dat and private key is all you need.