Doog,
Can't give you advice on attaching wings after painting... i never done it myself before and afraid to say something about that, my own logic would say don't but as far as fit goes i'd say that the wing/ fuselage join won't be much of a problem with some careful dryfitting and sanding before painting.
The hobbyboss wildcats have, however, two main points of concern: The attachment of the lower fuselage to the main fuselage halves can be tricky, getting everything to line up properly. And the biggest one would be NOT to follow instructions when it tells you to glue the pit assembly to the lower fuselage. It will leave a gap where the headrest bit should attach to the upper fuselage. This happened on all three of my wildcats.
Other than that these kits are very easy to assemble and smooth sailing all the way
Hope my ramblings are clear and helpful to you...
Richard