I can't use the internet without it anymore

ok

The only extension enlarges even Youtube profile images.

Search for updated versions of the sieves on "Imagus Reddit" (type into a search engine). There you should also ask your questions about problems with Imagus / Imagus Mod.

На Реддите невозможно писать комментарии, вместо этого срабатывают горячие клавиши. Только если отключать плагин на время посещения реддита

Doesn't have an easy accessible option to enable/disable on certain sites to my knowledge.

Occasionally, it stops working and the user must stop and start it to restore functionality.

Literally an essential once you start using it. It's one of the most usefull extensions for any browser.