Well, first things first, Tom...
In the Utility page, the is a 'Startup' button, takes you to a section where you can specify which UPG gets loaded at Startup (p.31 in the manual). So you can create a special UPG for when you power up that has everything the way you want it.
Secondly, with respect to the sliders...
As with all keyboards with sliders that are not motorized, if a UPG is called up where the slider's physical position does not match the stored value, you have to go 'through' the stored position before it will start to make a change. Trouble is, of course, if you don't have the slider (mixer) page open, you usually don't know if the slider's physical position is above or below the stored value
My workaround for this is to jam all the sliders to the top or bottom (depends on whether I think I am likely to want to change levels, or drawbar registrations - levels to the bottom, drawbars to the top) just before I make a UPG change. Then, at least I know I have to go in one direction, no matter WHAT I have to change. Then you pick up the stored value on the way up, guaranteed (if starting at the bottom).
At least it's better than the parameter 'jumping' immediately to the slider's physical position as soon as you move it. You always get a nasty surprise with that system! Bottom line is, if you open the mixer page (or HB section page) while you do this, it's much easier to see what is happening. You don't REALLY have to go all the way up or down before it latches, but if you don't know the stored value, looking at the mixer page is the only way to see it. Watch what happens on the screen next time, you'll quickly get the hang of what's happening.
Finally...
As to the drawbar registrations... The HB preset a UPG calls up is stored with the UPG. So, when you create your 'Startup' UPG, you can select which preset it will call up (and edit it to something different, if you want). Don't forget, as well, that the presets themselves are editable and storable... you can replace the factory settings with your own, for the eight upper and eight lower drawbar registrations, and store them. Just be aware that the HB Presets are stored in the UPS (User Program Set), as a global choice.
But, no matter which HB preset you have selected, the UPG itself stores any changes you make to the HB preset, so the eight HB presets are merely the jumping off point for a myriad of variations... (if you are using lots of different UPG's).
Hope this helps clear things up.
BTW... In future, could we do any Roland specific technical questions on the Roland-arranger forum? Half the time, any questions are answered by a simple 'search' there, and if not, at least the Q&A gets posted in a place where it may do someone else some good at another date, rather than lost in the clutter here at SZ. I monitor there as closely (or closer!) than I do here, so you won't get ignored...