Dunno why you'd want to spray paint a clear mag...
Only thing you might have problems with is the painting of the receiver. Although police will usually look that over if you're using it responsibly (eg. at games).
However please note that even if someone used a clear gun in a robbery it would still be considered armed robbery and the clear gun would be treated as if it were real (meaning harsher penalties).
Orange tip - only a US law, although in Canada there is a misconception that we require orange tips.
Trades - Only thing it might get you in hot water for is trademark/copyright infringement.
Dummy rounds - Not so sure, but I believe that they're OK (nothing comes to mind about dummy rounds). Plus you can get "bullet pens" and belt buckles and whatnot so I don't see why it would be illegal (visit here to get your very own bullet pens
http://www.awelldressedbullet.ca ).