=== How do I set up the wallet to be a full node (and why would I?) ===
A full node validates transactions and blocks, which makes the whole Ravencoin network stronger. You can enable this by opening up the wallet and looking under Settings > Options > Network and making sure both "Map port using UPnP" and "Allow incoming connections" are both checked.
=== What should I do to keep my Ravencoins and my wallet as safe as possible? ===
https://virtopia.ca/crypto-wallet-safety/