Hi Sailor Steve
Don't be nervous!

Remember, faint heart never won fair lady
A couple of tips: make sure you still have the original unpacked files for both U-jagd and Sim feeling. If there's a foulup you can always just throw away what you've done and reinstall the mods again
Secondly, make sure you've disabled both the relevant mods using JSGME before you start operating. Then remeber only make adjustments in the mod folders - never touch the main SH3/GWX install.
Then just go for it.
To answer the scope magnification question:
U-jagd tools does not change the scope magnifications. The scope magnifications are as they were in SH3 (x6/x4) or GWX (X10/x4.5).
This is the main difference with the different versions of U-jagd. The scales on the AOB finder are set to give the correct range for the appropriate magnification.
If you wish to use x6/x4, then you must make these changes yourself using mini-tweeker. After that, the you must use the U-jagd_DIY kit. Otherwise you use the U-jagd1.3.
seYou know what: just answer these two questions for me.
Firstly, have you already reset the magnification back to x6/x4?
Secondly, can you show me the link to the Simfeeling mod for GWX 2.0?
If so, I'll make the mod for you and send it to you. It'll only take me 10 mins.
joe