What software solutions are available to express math problems? I want to be able to quickly type complex equations (especially with common notations in Calculus) for printing and online sharing.
Tex is the most useful software for scientific and mathematical writing. See for example, http://www.math.jmu.edu/~arnoldea/latex_setup_and_tutorial.htm
You will have to learn the syntax, but you will never regret learning Tex, that is unless you only learn it to use it once. There are vast amounts of resources online to help you in learning this software.