I suggest you don't use rpcuser and password if you don't need to. If you don't set them, Bitcoin Core will use a cookie in your .bitcoin directory as a mean to identify you.

Besides rpcuser and rpcpassword are deprecated now, you're supposed to use this python script to generate a password and copy the output in your config file like this : rpcauth=[user]:[long random string]

But once again, I suggest you don't use it if you don't need it.

As for the alice username, it's just a common placeholder name originally used in cryptography, "Alice" and "Bob" are the two parties that try to communicate, Eve is the passive eavedropper that tries to snoop on their private conversation and Mallory is the active attacker that tampers messages or disrupts communication. I think there's no harm using it as a rpcuser name though.