Hey man,
I didnt
test
in gmail, but I tested in hotmail with similar results. The inline styles seemed fine, but I had to click an almost invisisble link for the system to download the css and apply it (which it did fine afterwards). Hardly intuitive and desired.
Your link will prove very helpful - however at first read, it doesnt appear that there is much that can be done in some of the browsers. For instance, that article states that GMail strips out anything from the header AND it strips out any style attribtutes. So even if we went all inline with styles, it would still look the same as above
I havent finished the article yet - but I will spend more time on it and see if a clever approach can be taken
As it stands right now, each element of the issues have their own templates (header, navbar, content, footer) so you will be able to customize these any way you see fit.
As to your module question, what you would be able to do is add it to a set and preview an existing issue (or generate a new issue) to preview until you like what you see - then finalize it... so basically... yes