By the way, this is all a good discussion.

As for Frege and geometry -- I'm not sure.  But he was probably aware that there are non-Euclidean geometries, which would suggest that the axioms of geometry are not necessary truths.

As for the general picture of analytic vs. synthetic, I sometimes wonder what that's all about.  There seems to be a viewpoint that analytic statements are of little or no value, and it is only the synthetic statements that are really important.  Or, at least, that's the impression I get.  I see that as a mistaken concern.