is it customary not to wear the color red or black on erev rosh hashana? I dont see it in the torah...a rebbetzin has told my mom in law this.

Red is never permitted as it states in Gemara Brachos 20a and in the Shach YD 178:3. Red attracts too much attention. On the other hand as far as I know, black is always permitted. Still a women should not dress too drab as to be demeaning.

thank you SO much!

isn't there something about not wearing the color of gold so as not to invoke the memory of the Golden Calf, as in the case of the Kohen Gadol on Yom Kippur?

I know that women shouldn't wear gold jewellery on YK for the reason you have given.

Not even a Wedding Band?