yeah wheels are actually kinda hard if the oil's soaked in, they care a lot about prep and cleanliness
But still, you can sand blast the old paint or rust off before powder so you dont need to, most shops can and will handle that
As for removing the spokes and hub, it's a very daunting task for most people though i'm not sure why - it's easy.
You need a spoke wrench that fits the spoke nipples. Take the tire off, take the rim strip off and back the spokes out (kinda seems reverse direction cuz remember you're turning esentially the bottom of the screw) and then when theyre off enough you can use a flathead from the top of the nipple. back them all off and good to go. tightening them back in you get the pattern right but that;s also easy on mopeds because the angled holes etc. and then get them all tight. moped rims are pretty damned rigid so if they're all close to the same tightness usually you don't have to worry about truing. You can true it just setting the wheel in some forks or back dropouts on the stand so you can spin the wheel. Use a sharpie or whatever held against a stationary part of the frame and while the wheels spinning move it slowly closer. it'll leave a mark on the parts of the rim that are bowed out toward that side, you find the marks and tighten the spokes pulling to the opposite side in that location and it straightens it out! wham bam whooodiddley