A number of answers:
Nope. Email is currently not supported by this plugin.
Never had this and am running the plugin in production on our systems. Is this still a problem? If so, can you maybe open the developer console and see whether there are any errors?
Not sure why this happens, but yes, if you use wrong syntax it renders wrong – #wontfix .
I am not using the MathJax plugin and incompatibility with other plugins might very well be the case. Can you tell me what exactly goes wrong and do you have an idea why? Might be an easy fix. I accept PRs on this if anyone cares about running both .
An update on the plugin? Sure the previously mentioned things might be valid reports, but I do not consider the plugin broken. As mentioned earlier, we are running this in production and I will continue to support it to the extend, that it works there, for us and any breaking reports.