I think part of the problem that the OP is sort of addressing is that we've spent so much time trying to gloss over the first-line failures of PGP, in terms of

I think part of the problem that the OP is sort of addressing is that we've spent so much time trying to gloss over the first-line failures of PGP, in terms of even getting a key to begin with let alone giving it to other people, that we don't even know if there are practical solutions to the problems you're listing. Every tool in this space suffers from the choices PGP implementations have made and asking what your uncle would do if trust conflicts occured when he's going to first be asked if he wants an RSA/RSA, RSA/DSA, DSA sign-only, or RSA sign-only key before he gets there, and then have to figure out what keyserver to send to and then.... Answering these high level UX questions requires having actual users.