Welcome to the forum and thanks for your question.
Shingles or not, you have been seriously overtested for HIV -- it's time to stop! The combination of result of your first DNA test at 4 weeks and your first antibody test at 5 weeks proved conclusively that you did not catch HIV. All test results after that time were superfluous. Below is the link to a thread that explains how and why results are conclusive at much earlier times than the 3 month official window recommended by most test manufacturers and public health agencies.
http://www.medhelp.org/posts/show/1704700
On top of which, you had an essentially zero risk exposure anyway. Condoms work!
To your specific questions:
1) Yes, absolutely conclusive. See above.
2) No, that's not an issue.
3) To the best of my knowledge, shingles does not occur with increased frequency during primary HIV infection. Even if it did, it would not affect my reassuring reply: the test results always overrule exposure history, symptoms, etc.
4) These tests are equally reliable.
5) There are no truly accurate statistics on false negative rates; all such figures are estimates. In any case, even if this figure is true, it applies ONLY to the antibody tests. So this is an irrelevant concern: it is not possible to have both a false negative antibody test and false negative DNA test at 4 weeks or more after infection.
6) I wouldn't have recommended any HIV testing at all after such an exposure -- and as I said above, all tests after your first two were unnecessary. You certainly shouldn't spend anything more on any further tests.
Really, stop worrying about this and stop testing. Believe the resutls you have had. In regard to HIV, there is no reason for you to delay having sex with your new girlfriend.
Best wishes-- HHH, MD