2. There are some built-in modules, such as Monternet, but you can take it to customer service and brush it into a regular version, as long as it is free during the warranty period.
3. The function is basically the same as that of 6 120C, but the maximum memory of 6 122C can be extended to 8G. 6 120C only has 4G.
4. It is recommended to download the latest PC suite from Nokia website and try it out.
As I said above, I can go to KF to brush. I also bought a heart machine for the N73, so I brushed the regular version in KF. You can brush it yourself. As for how to brush, you can go to some smart phone forums, and the above tutorial is very detailed.
6. There is no difference. Feel free to use it!