Lately I have many registrations with weird user names and emails, for example f23z35ftk, lianacvv2e3z5k. I delete them, but sometimes there is hard to distinguish human from bot.
I was looking for plugin, that will show user activity: register date, last login (if any), pages visited. There are many plugins with various functions, but maybe you found something interesting?

I tend to delete most of those, especially if the name bares no resemblence to the email - or if regular emails crop up with variety of names.

I am currently trying out Wordfence which seems to show a lot of the things you have asked about - have banned quite a few Chinese isp numbers so far, rightly or wrongly I do not know