Off.... The UV argument is bull... The other four tires are seeing as much UV exposure as the spare is, and they also see a lot more heat and expansion and contraction from use. I hit my tires with a tire cleaning product at least a couple times a year, whatever is your favorite use it, but just make sure it has actual protection properties and not just one of those cheasy tire shine products. Its more of a rubber conditioner/protectant than just making it look good.
As for rotating... I have never rotated in the spare on any vehicles i have owned. I was on the fence about it for a while with the KJ, but i'm going to leave the spare unrotated.. Why? Well the one time i did this, my old S10, i must have picked up a small nail and didn't know it and that tire ended up as the spare after rotation, and then when i needed my spare it was half flat... Yeah i know i should have been watching the spare tire pressure but i hadn't checked my tires in about a month and then i got the flat and found out i had a half flat spare.
I know there is lots of arguments towards including the spare in the rotation as well.. i just haven't been able to make myself do it. I just got new tires on, i will go a little longer yet before my first tire rotation on those, and then i will decide if i should include the spare. The only thing is the other four will already have some wear, so putting on the spare now will have one tire with no wear, and i have seen on here time and again about how the tire wear affects the 4wd shifting out. I guess i could put it on the back but then i have a slight difference in traction back there also.
I don't know....
