10 characters
Data enters are in Chicago and Los Angeles There is no NY data center. Both data centers have realms for every US time zone.
You may also want to check out the guild recruitment forum.
Oh, I was looking at the WoWWiki which must be outdated as it listed realms on a New York Datacenter
Yeah, wowwikki has been outdated for a few years now. Most of the authors there moved over to gamepedia.
Just as an aside, wowhead is still the top reference site for game related info.
Icy-veins.com is the goto place for class info.