I've never resold hosting before so I'm a bit unclear as to what the demand is. Do you prefer that the company you resell be completely anonymous as far as name servers, mail server, etc? Generally how much is the markup? Do you do everything including setting up DNS, billing, etc?

Please detail what resellers needs are. Thanks!

Yes most people would want their own private-label hosting company; therefor, the nameservers would have to be anonymous or their own. And as for billing and suppot, your resellers provide this and you in turn support and bill only the reseller.

Do most hardcore resellers own their own domains and the name servers are ns1/ns2.reseller.com? Same goes for mail. I would assume most often the IPs of these names have the same IPs of the company the reseller is using.

Yes, otherwise they would only really be affiliates. A snoopy customer may search into the who-is of the reseller and see your nameservers. From there the client will probably buy direct from you instead of the reseller.