i host with hostmonster.com

my website; adhocracymgt.com is hosted with hostmonster.

they changed A record on their servers for me:
adhocracymgt.com -> 'their ip address' for my website (Web is hosted at Hostmonster)
mail.adhocracymgt.com -> 'my ip address' (Mail is hosted there on my server)

this is what they said is on their server for live mail records:
adhocracymgt.com. 14400 IN MX 0 mail.adhocracymgt.com.
mail.adhocracymgt.com. 14400 IN A
i want to install zimbra open source in a production environment to be accessed from anywhere on the internet.

Email addresses have to be, e.g. xxxxx@adhocracymgt.com

My 1st question is; what network settings do i need to get this working.

Current settings:
External IP Address  xxx.xxx.xxx.xxx
Domain Name Server  xx.xx.160.x3,  xx.xx.160.x4 (of my isp)

Internal IP Address
IP Subnet Mask
do these settings need to be changed?

2. should the hostname of my ubuntu installation be; adhocracymgt.com or mail.adhocracymgt.com

3. in the network settings for ubuntu, in the nameserver section, do i put
my isp's nameservers,
hostmonsters name servers
make up one like or
(I'm pretty sure its not the last one but just to make sure )

once i have this setup i can go ahead and install ubuntu server.

after installatation first thing i have to do before installing zimbra is the DNS settings, which i have no idea on how to do. I have looked through this forum and google, and tried many a few tutorial for DNS/bind setup, but i still get a DNS ERROR when installing zimbra.

If anyone can help me with this, i would greatly appreciate it and if i can get this working, i can buy the network edition for my company.

Thank You