How can I export/import contribution pages and event pages from one site to another
It should be possible (but I've not tried it ...) using the API for Event and ContributionPage:
civicrm_api3('Event', 'get', ...) to get them from one system and 
civicrm_api3('Event', 'create', ...) on the other.

Take a look at the API explorer on your system (Support >> Developer >> API explorer).

Unless you have loads of them, it might be just as quick doing it manually!