I want to start writing some answers, but I think it would take a long time to write a quality answer, because I don't have much experience with latex for formulas, also I don't have much experience in computer graphics, but I am eager to learn and share my knowledge.
For working on an answer before it's ready to post, the site has a draft saving feature. If you start typing an answer and wait for a little while, you will see "draft saved" under the text box. Then, you can come back to that question later and the site will automatically restore what you typed before. You can use this if you need some more time in order to write an answer and you don't want to do it all in one sitting. (Be warned though, the site only saves a draft for 1 answer at a time, so you don't want to go answering another question before you finish the first one.)
Also, you can definitely edit answers and update them, even months or years later, and it's good practice to do so if you find errors or if new information comes to light, e.g. if there is a bug in a code sample you posted, or links have gone dead, or there is a new paper out, or a new GPU feature that is relevant for the answer, etc.
With regard to formulas, just do the best you can, and if you post formulas that aren't formatted as well as they could be then it's likely that someone else can come along and help you fix them by submitting a suggested edit for your post. Also, you can hit edit on anyone else's posts and see the LaTeX source they used, so that can be a good way to learn some of the syntax if you see someone else using a lot of formulas.