Deep knowledge of TeX is required only if you need to edit the template (plus it's a Pandoc-powered version of TeX, so it's a bit different), but for editing the content Markdown is the only language needed.
You may find some TeX in "math mode", where formulas and matrices are declared, but it shouldn't be too hard and in any case I can give you a hand.
There's no need of being a master in either Markdown nor Git, if you can write text and do the usual push/pull/commit operations (plus maybe solving some merge conflicts that may arise) you're all set.
If you have any questions, feel free to ask!