Thou shalt not oppress the ger, or should you?

This letter from an anonymous gyoress is going around some conversion blogs and online discussion groups.

http://www.jewishideas.org/anonymous/thou-shalt-not-oppress-ger

A certain rabbi commented on this very harshly. However, I'm seeing he seems to be a little more reasonable about it now. One of the highlights from the article and his response is:

She writes: "The basic problem a convert faces in the Orthodox world stems from
the following mind-set: If you observe one mitzvah more than I do you are a
fanatic, and if you observe one mitzvah less you are an apikores, or heretic."

rabbi: This is most unfortunate. Does this mean that where she lives the
"Orthodox" Jews specifically do not keep all Mitzvoth? I've actually written a
warning about marginally Orthodox in Gerus Steps. We've occasionally run into
people like this. If this is her idea of "Orthodox" then her synagogue does not
have an Orthodox minyan. I would like to make it clear (I know that I'm being a
bit redundant) that merely living in a place without a community may not
invalidate a conversion but it certainly is far from the ideal and can lead to
many problems. What sort of education is her son receiving? Is he exposed to
true Orthodoxy (and I include Modern Orthodoxy as true Orthodoxy) or something
less?

Michal: If the author is using the term mitzvos as the rabbi does, as in mitzvos, then yes, his rebuttal is perfectly fine. However, it seems to me that when the original author said mitzvos, she didn't mean the precise 613 mitzvos, but the chumros (stringencies) that people glue upon themselves as a loud and proud statement of, "I'm frummer than you are." One kollel wife told something like real Jews wear the black velvet kippah and if you wear suede, you were never on the derech.

I would hear Heshy Fried make fun of this stuff on his Frum Satire site and I thought I was removed from this narishkeit. "Surely, my friends wouldn't think like this." I was wrong. So, perhaps the author is pointing out the people that think someone who drinks cholav stam milk is an apikores or those who think that you have to wear a certain kind of kippah to be frum.

As I understand it from the bubbies and zaidies that in their day there was no requirement to wear black and white. However, I had man tell me he is frum because he wears black and white.

I also know of another story. An FFB man was in the parshah and a prospective shidduch turned him down because he was wearing a dark brown suit on the (first) shidduch date. He did marry a wonderful girl. However, why is it that no one sees this as riduculous. Also, people like this see "dressing Jewish" like this as a mitzvah. I like to joke that things are the 614th mitzvah. I started doing this before I really knew the extent to which these kinds of mitzvos are added.

Finally, will somebody please tell me, where in the Torah it states that men must wear a black velvet kippah. Why is a black kippah of another material assur? How about velvet of another material? Why can't a man wear a dark brown suit or a dark blue hat and still be accepted?