There is the normal "post a reply" page as well as the "quick reply" button, the latter of which is far more minimal. If your internet had a brief hiccup it's possible that a stylesheet or the smilies didn't load properly, but a refresh should fix that. Things might also appear differently depending on whether you're using the site from a PC, your phone or something else. The usual advice in these situations is to clear your browser's cache.
My first guess for the banananananas would be that options for them might not appear if you get logged out (happens from time to time, cookies don't last forever). Second guess is that there would be that there could be some kind of rate limiting going if you gave or took back a lot of banandanas in a short space of time. There is an option on the settings to enable notifications if you get given any, so there is probably something in the code to prevent abuse of the feature. Features like this tend to inherit things like that directly from the underlying forum permission groups, so it's plausible. If that is the case, I'm not how long a timeout would last, but I'd guess 5, 30 or 60 minutes.
You can check when a user was last online by looking at their profile, but that won't work for those pesky users who log in as hidden unless you're in one of the all-seeing and almost-all-knowing user groups.
There haven't have been any changes to the site recently. Our dear admin hasn't been around for a while, there is very little evidence as to what might have happened to him...