Is it possible to have multiple active keys in an account? Say I wanted to have one at home and another where I want to share with a person I trust.
Yes, this is possible (example). Any permission (owner/active/or otherwise) can have many keys associated with them (not sure the max limit).
You will want to include the new key with a weight of 1 (same as your original key), and leave your active permission's threshold at 1.
You can do this here, but be very,very,very careful: https://toolkit.genereos.io/account/advanced