first of i dont know witch firmware version i have and even if i knew i wouldn't know where to download it.
id also like to know if it really matter to flash with the same FW version i already have.
and at last i wanna know why the FW comes in to files one being "fs" and the other "main" and what i need to lock for in order not to pick two incompatible?

im very thankful for any answer!

You have to connect your phone to XS++ to find out your firmware, and you don't have to flash the same firmware you had previously, you can flash any firmware thats compatible with your phone. MAIN is the actual firmware itself, while FS is the File System that the phone itself uses in order to work alongside the MAIN, it's highly recommended to use the same MAIN & FS, although there are certain occasions where the MAIN and FS can differ in order to achieve a modification. Firmware can be downloaded here, here and here

thanks a lot man!

Welcome, you are...