My DH & I married in November, and the day before our wedding was perfect! Warm, sunny just perfect, and the day of our wedding, it pourded down rain. I have been told that November is one of the most unpredicable months for weather.
Went sent our invites out with 2 months notice, but that's because everyone knew the date anyway and had put it aside.
As for the dress... look in cheap shops also. There is a place that sells fairly cheap formal wear that can come in white/ivory etc and some of the dresses are $100 or so.
I just asked my DH and he agreed that we would definitely attend Thursday wedding... I think most would.

All the best!