“a. It’s a step upward, since the yarmulke is larger” – if that increases your yir’as shamayim, then yes.
“b. It’s a step downward, since leather is better than knit.” – if we were discussing tefillin, that would be correct.
“c. It’s a step upward, since it’s black, as opposed to blue” – the purpose of a yarmulka is to strengthen yir’as shamayim. that being the case, blue may actually be more useful for that purpose, because it’s “similar to the sea, which is similar to the sky, which is similar to sapphire, which is similar to the kisei hakavod.”
“d. It doesn’t matter, since you’ll never see a gadol wearing a knit OR leather yarmulke, so you’re doing wrong either way.” – that’s not true. there are gedolim who wear knitted and leather yarmulkas.
“e. It doesn’t matter what the yarmulke is made of, what color it is or if it’s bigger or smaller (provided it meets the minimum halachic size), so it’s neither a step upward or downward.” – it’s very unclear what the “minimum halachic size” is. i think, if it helps your yir’as shamayim, go for it! if it hinders yir’as shamayim, don’t. and if it makes no difference, why not?
“f. You’re a known kofer, so you’re better off not wearing a yarmulke anyway.” – ummm…………. no comment.
😉