In the future, how would I go about updating electrum? What command would I use to update?
The same way you installed it i.e.
sudo pip3 install <tarball>
pip3 will uninstall the old version and install the new version for you.
I strongly suggest installing using pip3 instead of relying on your distro's repos. Electrum has a very fast release cycle and most distros don't keep up with the latest. Installing from source will get you the latest and greatest. I also strongly recommend checking the gpg sig before installing. This script automates all that for you.
Wallet files are stored in ~/.electrum/wallets. You can also backup the file via file menu > save copy. More about backing up an Electrum wallet here.
In case you are wondering wallets don't get removed when you uninstall electrum. This is to prevent accidental loss of funds. When you update Electrum it automatically picks up your wallet from the default location I gave above.