Hangar Flying

I acquired a partial build Long Ez project.  The wings are bult to the point of cutting ailerons and adding winglets, the canard is built and the fuse looks like a stubby canoe ready for a nose, center spar and strakes.  Overall the work that was done seems pretty good quality but thats based on my untrained eye.  I did have the local Canard owner take a look as well and he agreed that the work looked good.  I do have a couple questions for the group;

Are there any types of non destructive testing I can do on the work that has been done to ensure it is airworthy.  I did learn a little about the "tap" test in my repairman school but wanted your thoughts.

Can you tell the type of epoxy used by the cured color of the parts?

Is there a problem using different epoxy with already cured parts?

What are the Epoxy recomendations now compared to what was used years ago?

Regards
Eric