Default [Q] Flashing from Cricket to Page Plus?

Hi there, I'm new to the forums so apologies if I come off sounding like a newbie.

I recently bought an SIII off eBay, and the carrier is Cricket. I wanted to know if it could be flashed to Page Plus without much trouble.

It also has a SIM card slot, but I don't have a card for it. Will it matter if I have a SIM card or not, since it's a CDMA based phone?

Thanks in advance to anyone who can help!