- I think the guider's number of stars and SNR stats should be thought of as relative measurements. That is, you see what they are when the guider starts, but their absolute values may not be too meaningful. As you point out, they depend on the star field in the guide-camera's field-of-view, and the SNR also depends on the brightness of the guide-star that happens to be chosen. So, when you do a meridian flip, the side of the image that the OAG picks off changes to the other side of the image, and the stars there are different.
Currently with SEP MultiStar guiding, even though there are many stars used to evaluate the drift, one star still is the "guide star" and that star's brightness helps determine the SNR. Admittedly, I should change that, but it's probably not a big deal in terms of guiding performance. BTW, I'd recommend you use a lot of reference stars--I use up to 50.
- Usually backlash doesn't affect RA, as the RA motor is running all night. Typically guide pulses are much less than the actual tracking rate so all the guiding in RA does is speed up or slow down the tracking rate, but the motor doesn't change directions. Think of it this way. RA tracking is roughly 15 arc-seconds/second. You'd need an error in RA of > 15 arc-seconds towards the East with 1.0 aggressiveness to completely stop the RA motor for one second. Therefore the motor is always turning the gears in the same direction and there shouldn't be backlash. (This is not true in DEC. DEC isn't tracking, typically, therefore you do change direction in DEC, and backlash may apply. That's why people talk about backlash for DEC.)
You may have large periodic error. This would cause variation in RA that the guider is fighting against. Assuming your mount supports it, you can load a PEC curve to counteract that. That is also what GPG tries to fix, but of course, it would be better if it didn't have to fix it, or didn't have to fix it as much. I have an experimental piece of code that computes and uploads a PEC curve with Ekos for my A-P mount, but only have one volunteer who can help with the testing for EQMOD mounts. It definitely helped my RA performance, though it was already pretty good. See indilib.org/forum/wish-list/5267-softwar...od-mounts.html#93921 if you want to also help test. Of course, you can always use a PC and upload a curve via pempro or theskyx.
- Widgets and the mouse scroll wheel: I agree with you that it would be nice if the scroll wheel didn't adjust the widget until the widget was clicked. This must be something buried inside of the Qt widget library, and we're likely using the default. I'll try and google it to see if it's something that could be changed--but i wouldn't keep my hopes up.