Hi Hope,
I do not have the Pb360 plus, only the PB360, however:
1) as far as I know, the system font is not the same as the browser font. For the system font, you should be able to change it from the configuration menu. As for the browser font, I think the solution is in
this post (the firmware for the 360+ should be along the lines of the Pro, so it should work fine on your device).
2) with the new firmwares of the Pro (so also the 360+), the games directory has been replaced with the "applications" directory, so this is how you should rename it - if you look for recent posts by violetdreams, you'll see she had the same problem.
No idea about 3.
As for FBreader, if it works, great - I think the worst that can have happened if you have not changed its filename when copying it to your device is that now when you "open with" fbreader you only get the FBreader 180, and not the original one. If you want to use both, you should rename the FBreader 180 app file and change the configuration file to tell your device that it can use either reading software.