I'm definitely not a Coppermine pro, but I can offer you some pointers based on my experience:
1) You shouldn't need to move your {custom_header}
2) You ought to be able to get (at least) your image to appear. Maybe also try:
../../wp-content/uploads/...
1) You shouldn't need to move your {custom_header}
2) You ought to be able to get (at least) your image to appear. Maybe also try:
../../wp-content/uploads/...