Hi
Q1: Not that I know of but i just flashed a K610 to W660 so im not fully up to date.

Q2: I really can't tell yet, but then i don't use SE's own Cam and Acoustic files but custom files that hard working people have released for us.

Q3:Well i can tell you as much as radio won't work, that is if you convert K610 to W660 because K610 doesn't support radio at all. It's in the hardware you know.

Q4: I don't know if Moby Explorer can view word files, haven't tried. But you install moby explorer as any other .jar file.
Just upload it to your phone, somewhere, doesn't matter and then just click the file in the phone and it installs.

As far as flashing your phone to W660 firmware... you have CID53 you write.. im not familiar with that CID and its procedures so sorry i can't help you on that one.
Best of luck though!