I'm a newbie with some technical skills, but not a lot.
Should I be using MetaMask for added security?
What does MetaMask do for me, exactly?
Also, MetaMask seems to only work for Ethereum-based coins. Is there an extension like MetaMask available for the other coins?
Metamask is one of the great ways to store ETH and ERC-20 tokens. Metamask is also recommended by Myetherwallet to ensure the safety of everyone's property. Its security feature is very good, anti-stealing private key when logging in and when you visit the fake sites it will have red alert to help you avoid being cheated. In addition, you can also easily unlock your MyEtherWallet with Metamask and can create multiple wallet addresses. I think you should use it. This is just my advice