Be sure to try out GNU Octave
and others for question 2 you find them in package manager. Use only package manager or yum for software installation as much as possible. Kile
is the best choice for sure just use package manager to install in not anything else, just simply:
yum install kile
And that is all.
If you buy Wolfram Mathematica 7 you can contact their customer support and they will help you to install it on any popular Linux distribution, they support it and that is their job not oss community. (http://www.wolfram.com:80/products/m...ica/index.html
Still I suggest you to try all GNU alternatives you can find before you buy that software.