You're right, Monty, the contrast between the appearance of the Norwegian Bf 109 and the Jaluit TBDs is remarkable. So far as we've been able to tell, no paint remains on the Devastator wrecks (though it's possible some remains protected beneath the marine growth, or on the shaded underside surfaces, or is too faint to distinguish in the available light conditions). The colder, deeper, darker waters off Norway (beyond the reach of damaging UV rays and hostile to many organisms) seem the most likely explanation for the surviving Luftwaffe markings. Aside from cosmetic appearance, I personally suspect that sunken American torpedo bomber is actually far more structurally sound than this lost Axis fighter.
Yes, Peter Fix and his colleagues at Texas A&M are working hard to outline the procedures needed to prevent the TBD deteriorating from within once it is removed from its long salt water submersion as part of TIGHAR's comprehensive Devastator Project recovery and conservation plan. There would be no real point in removing the plane from the environment that preserved it for nearly 70 years, only to see it corrode into nothing.