I know what you mean about the nuts on the landing gear. All mine are glued in, I learned on the first one. I don't remember if there is any overhang on the axles or not but if there is : cut a small piece of fuel tube and slide it on the end of the shaft. Sometimes that will give you a warning if the nut loosens up. Also you can get Nylon lock nuts at Home Depot or Lowe's. I'm not sure but I think they were # 4 metric.

As far as painting the prop, I wouldn't. You might paint the tips Blue but that's all I would do. Then you are going to have to rebalance the prop. Also I don't use many wood props anymore, I like the plastic (?) ones. When you get your new props, try a 11x5.

By the way, if you ever get a chanct to get a " READY " by modelfly I think you would really ENJOY it. Both the Jupiter and the Ready do a super inverted flat spin but I think the Ready does it a little prettier. Maybe it's me.
ENJOY !!! RED