OK yes u can paint that band u want around the tubes but i advice you to sand to etch the surface a little bit so the paint has something better to grab on, then clear over it. On the clear dont even dare to put crylon or anything similar because that could burn the powder coating clear and sure u dont want that. Use U-pol #1 is a spray and is safe to use over the PC job u have in there and wont get yellow because it has UV filters, cheap clear gets yellow after 6 months big time. The u-pol is like 15 bucks, too good for the quality and probalby you will be able to ride the bike next day with this stuff because dries to the touch in 15 to 30 mins. Krylon and other ones are just garbage.

As for the decals, just apply them after u paint, then clearcoat over it.

Sand slightly 2000 grit, paint the stuff u want, apply the decals, then clear. Then to finish you can sand the clear and polish (this one depends on you)