I’m nearsighted, about -3.25 diopters. For daily work, I use progressive lenses. For golf, I have single vision (no reading/progressive) sunglasses, as you do.
a) Yes, I lift my sunglasses as needed to record scores, adjust pin/putting location, etc. I’ve never really thought of it as a problem, but I can see how it might be for some.
b) For low light, I have a very inexpensive set of single vision regular glasses that I ordered online ($50 or so because I splurged and upgraded the lenses). I keep them in my golf bag all the time. At dusk, I switch from my nice sunglasses to my cheapo clear glasses.
From time to time I consider contacts (I’ve worn them in the past), but then I’d probably have to use a set of readers to deal with (a).