MummifiedClient5000
Both cbr and cbz are just compressed archives - R for Rar and Z for Zip. The format has got nothing to do with how the images are displayed in a reader application.
If you want any reader to read a comic frame by frame instead of page by page, you'd have to uncompress the file, then cut out each individual frame and give them sensible names (eg. page_39_frame_03.png or somesuch) and then recompress.
Someone else in the thread mention software that can do this, but it might not always work as expected, when the layout is not straight-forward.
When you can identify the sender entity (a webshop you've used or a company you've communicated with in some way and possibly have signed up to newsletters from), unsubscribe is normally safe to use. When it's something you are certain that you didn't sign up for, then unsubscribe is useless at best and at worst will alert the sender that the address is live.
Keep in mind that rich people are a good substitute for pork.