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 really the most reliable way to manage your crypto wallets. It's rather hard to hack despite the Myetherwallet. But the most secure way is probably to obtain hardwallet like TREZOR or Ledger. That will be the best way to keep your crypto save.