As soon as logical and moral truth becomes subjective (because there is no God - no objective mind), it is therefore no more authoritative than a persons favourite colour. One day 1+1 might equal 2, another day it might equal 5.
This is where we differ, and I say that developed cultural consensus provides authority to morality from which truths are developed. You can apply exactly the same to logic, which is an evolved, developed, human cultural phenomenon, not a transcendent phenomenon. Cultural, moral and scientific consensus are how truths are arrived at.
Aside from the above clarification, I have no problem with your epistemological argument, as it's pretty much stating the obvious.
Your aposterioritic argument is just a theologically wordier version of "there must be a 'first cause'", but simply positing that "Goddditit" may solve the 'first cause' problem for you, but is not evidence in itself, and MUST be backed up, as it's entirely unsatisfactory for non-theists.