P.S. Is it possible to change "preview"s sizing? Most important parts of pictures above is these green arrows. On the upper pictures arrows are hard to see.

If this small images of pages are what you are calling "preview" then yes, I mean preview autoupdate.

I want to set different refresh intervals for different groups, for example: [5 min] for group [social websites], [1 hour] for [manga], [never] for [torrent trackers] etc.