You say you're using the w2k dns server so I will not be able to provide you with specifics on how to configure your server. But I'll help as best as I can with generics.
to modify mail.mycompany.com you may do 1 of 2 things.
1) Create a zone for mycompany.com
Then you can set whatever records you want for that domain. More specifically, you can add an 'A' record for the mail host.
2) Create a zone for mail.mycompany.com
With this minor hack, you can modify the records for that host only, and leave the www.mycompany.com
etc alone. More specifically, you add an 'A' record for the origin (zone root).
I have no clue how to enable recursive queries in w2k dns server. Doing so is also kind of like setting up a caching server, as opposed to an authoritative server only.
As for forwarders, I'm not certain what you mean. If what you mean is that the server will recommend certain "forwarder" dns servers if it can't resolve the request, then you can do that too. By default a server recommends the root servers (a.root-servers.net etc). But you may also choose to recommend the ISP provided DNS servers. Another option is to specify in your DHCP the primary server to be the LAN dns server, and the secondary to be an ISP provided server.