Great move....many have upgraded from 7650 to 6600 and have not regretted doing so.
Answer to Q1
3.42 is the most recent....3.48 is apparantly due in Feb 04
Answer to Q2
128MB is the largest recommended by Nokia, but many have successfully used 256MB. Search the forum for more information as to which makes are compatible.
U have to contact the software author. Ask them if the latest version or latest build of the software download will work for your firmware version or try to install... if it works.. .. if it doesn't work :( .. let them know
i just made the upgrade from 7650 to 6600, also mainly for memory.
i have half filled the 32mb card, but simply because most of my apps don't work with it :(
apart from that though, this phone is amazing with everything from appearance to ..... whatever else you can think of especially compared to 7650 which i have give to my sister.