new XV6800

[Lateadopter]

My XV6800 arrived yesterday. I know this phone has been around a few years, but I wanted a smart phone with wifi that I didn't need to have a data package with. I have a few questions. First should a continue using the mw 6.1 that came on the phone or can I upgrade to 6.5. Second, verizion is telling me that micrsd will only support up to 4gb. Is this true, or can I buy a 8gb or 16gb?

What else should I look to change on this phone to make it run at its full potential?

thanks