Log Shipping - Secondary Database(s) - Which recovery model?
The recovery model for the secondary will be the same as the primary database, because you're backing up the primary, restoring it on the secondary node using NORECOVERY/STANDBY, and then restoring subsequent log files to it.

In a log shipping configuration, you cannot make changes to the secondary database. If you could, then the databases would be out of sync, defeating the purpose of log shipping as a DR solution.

Edit: The Microsoft documentation is fairly comprehensive regarding the basics of log shipping and the requirements for it.