Difference between SEUS and XS++:
XS++ replaces the whole firmware if you upload the files (which implements the fact that all your personal data will be lost, you'll have to create a backup or copy your contacts etc. to the memory card) while SEUS just changes some parts.
If the problem is firmware related it's likely that SEUS might not fix it.

You can find the suitable firmware by clicking on "languages description" on the mainpage. This is also stated in my tutorial which you already read ;)

Connect your phone to XS++ to find out your CID.

In short: Read my XS++ tutorial again and take some time to really understand what is written down there. All your questions are answered there (all but the SEUS<->XS++ question).