Questions on browser cookies

So, I went from about 80 to 50 apps on my phone which feels pretty great. In the past, the Android web experience would be pretty terrible compared to the app. This is not the case anymore, so I made a bunch of browser links and deleted lots of apps.

I usually don’t save any browser cookies, but now the only minor complaint I have on my setup is that I have to login on all these websites that replace the apps. If I save cookies for those sites to remember my login info, what kind of information would be stored aside of the credentials?

Essentially, the question would be, what is the extent of the information that can be stored in cookies? Can I decide that only login information are saved with nothing else but that?