Touch My old & new Kobo touch. Setting up

I have had a Kobo touch for a couple of years.
Am thinking of buying a newer one and giving my old one to my daughter.
Not bothered about Kobo books i have read on my old one But have many sideloaded books on it
Can they stay on it?
How can I change the user and email address on it?
Also cannot remember how to set the new one I bought up.
Can I keep the same email address?