The simplest acceptable version, according to our findings, is to let the user enter math formulas using LaTeX (and then use mathjax or equivalent to make them look good). But for more complex figures to force them to create an image or an SVG of it. If users get to choose one more figure type they want to be able to edit through the web editor, the answer is usually tables.
yes, both. Both depends a bit on what the formula is used for. We have listed them both places.