Will the Freedom mini work with the 650p?

Can't say from personal experience, but this site sure says it does:

Treo-Gear.com - Freedom Keychain Treo GPS

As long as your navigation software support external GPS units and uses NMEA then it will work fine.

what navigation software is suggested to use with it?

I use TomTom 6, but any one that supports the Bluetooth serial port profile (SPP) will work.

Yeah personally I would recommend either Telenav or TomTom (most of the people in the office here use Telenav and it works very well).

Thanks for the respons, great...

does this use airtime minutes, or the web browser?

None of the above, unless you opt for a package that needs internet service (for real-time traffic and such), in which case it will work however your data plan is set up.

With my setup, I don't need internet service. Just TomTom Nav 6 with a bluetooth GPS receiver.

for Treo 650 there is one cool appl. and lots of stuff over there to download such as video ringtones, themes, cartoon network and many more.