So there are several ways to express something is "seemingly not ～":
4) ～そうにもない (is this one even real?)
I was always taught ～なさそう in my Japanese classes, and it was not until I heard one of the other ones that I ever become confused about them.
After doing a little research on this, it seems that adjectives can only take ～なさそう. ex.
but that verbs can take any of the forms
○ 雨が 降らなさそう／降りそう（に・も・にも？）ない
So, my questions are a) is the above reasoning correct, and b) what are the differences/nuances of the forms in 2,3,4? Someone please set me straight on this; it's been bugging me for a couple years.