Thank you.
AFA containers, TBH, I haven't looked into them yet, not even for general use. I will get to them one of these days.
There isn't any WE API to allow context-menu to be updated before it is shown at the moment so I can't add a reload count to the context-menu. Adding a marker (e.g. in the tab title) could be possible, but that requires getting into page content which FoxyTab isn't aiming to do. However, I can add it to the toolbar button pop-up, once I write the feature (another feature was also requested that could be added there).

I will work on it for future updates.
Please post all support questions/requests to the support topic.

Thank you. Open which links in private tab?
Please post all support questions/requests to the support topic.

The Non-WebExt works until FF57 and should continue to work on Pale Moon. AMO will not accept any update to the non-WebExt version anymore. The features are identical (except that the v2.0 also has a contextmenu icon). If there are any issues, let me know via the support page and I will see what can be done.