I'll try to ask around next week and see if there's any info I can get.
Oops I posted the answer on my wall. Guess I'm tired. LOL
You're welcome. Glad I could help.
I think the number of nbrs depends on your style of playing and how often you play. Having a lot of nbrs can be a burden. The game limit on requests is 20 a day. You should have twice that many since not every one plays everyday. Don't feel bad about deleting those that don't visit a lot. Both my cities have over 100 nbrs each. I visit those on my wall then regulars and those with highest social ratings. I can't add more due to lack of energy. I can't keep enough buildings clear so nbrs can visit.
Yes the news feed doesn't hold very many cities that's why I tell people to post on my wall when they visit. I still get a lot of visitors and nbrs that don't post on my wall. Their names get bumped off my news feed before I see they visited, so they don't get return visits.