I think if you look around here, you'll find lots of people had some adjustment getting used to the people in their chapters. Sometimes it works, sometimes it doesn't. Like I said before, ultimately only you can figure it out, and at the risk of a cliche, it's likely to be what you make of it.
As to your name,
I'm sure no harm was intended. But now you know that most fraternity and sorority members would consider it a very big deal.
Like VandalSquirrel said, some people find it very offensive, but not everyone does. Most fraternity HQs heavily discourage use of the word because of the Animal House/frat boy connotation.
(No stupid or profane analogies are needed beyond that.)
Like I said, most members of fraternities tend to care a great deal.
The point is, if you're asking people for advice, you usually get further if you don't offend them. Calling yourself "KappaSig" when you're not one yet and using the word "frat," even if the brothers in the chapter use it, are pretty much guaranteed to offend a good number of people on a Greek chat board. It is what it is.
