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?
yes you can use metamask or you can also use myetherwallet to receive a coin that suport ERC20 and make sure you keep the secret key used to get into your wallet.