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 only designed for Ethereum wallet. It is an added security so yu don't have to put your private key on a decentralize trading platform like Etherdelta. I only use it for trading purposes but i do not use it for storing my Ethereum token.