Hi beddyboop,
You will normally find that any issues with static electricity would be from handling the latex and once a mattress is put together and covered and you are sleeping on it then it’s no longer an issue.
If you are using a grounding sheet then the latex would be underneath the sheet and I don’t think it would have an effect on the effectiveness of the grounding but I wouldn’t consider myself to be an expert on earthing (even though I do have the earthing book and am an advocate of earthing).
Latex in general is also the most breathable and “temperature neutral” of all the different types of foam materials but the firmness of a mattress and how much you sink into it can also affect sleeping temperature as well. While it’s also not always possible to to track down temperature regulation issues for any particular person on a specific mattress because there are so many variables involved (including your room temperature and humidity, your sheets and bedding and bedclothes, your mattress protector or any mattress pads you are using, and where you are in the “oven to iceberg” range) and some people can sleep warmer on mattresses that most people are generally fine with … there is more about tracking down a potential cause or causes for temperature regulation issues (at least to the degree possible for a specific mattress) in post #2 here and the posts it links to that may be helpful.
Phoenix