I personally keep my identities separated across platforms as well.
To address the problem of naming, I keep a list of names in my notes app. Sometimes strings or sounds cross my path which light the "this might make a good name someday" bulb in my head, but I can't recall them on command without writing them down then looking them up.
I find it helpful to think adversarially about what I say: If I wanted to track the person behind any of my accounts to a physical location, how would I do it? Being my own attacker helps me draw lines between what I find it appropriate to share where. Every bit of information that you share under the same identity increases an attacker's odds of finding you. For instance, sharing what company you work at is safe. Sharing what type of work you do is safe. Sharing what age you are, what gender you are, what ethnicity you are, what part of town you live in -- all safe on their own, but if someone had all those pieces at once, they could probably pinpoint you as a unique individual and look up your details in public records to find your address.
I decide whether to disclose information by how unambiguously it pins a given account to my physical identity or to another account. It's almost always fine to share superficial detail about a hobby, as long as a lot of people do it. For instance, you can share that you like playing reed instruments, or that you enjoy keeping fish. But if you get into greater detail -- if you build and play reproduction 17th century oboes, or if you're a regional champion competitive koi breeder -- you've probably doxed yourself.
It's also worth being clear about why you're separating your identities. I do it because I plan to live in the same place for a rather long time, so having my location found by anyone motivated to cause me problems would be disproportionately inconvenient.
Escalating acquaintanceship into friendship involves increasing trust and disclosing more personal information, regardless of whether it happens in physical or digital places. I think you'd do well to look closely at what you think others would gain by filling out the quiz that you propose, and look for ways that you could offer that to them directly with a lower chance of accidentally sharing more than you want to with someone you'd prefer to keep at a greater distance from yourself.