I can't help you with DNS configuration in M$. In UNIX, the serial is for slave authoritative DNS server to compare it with the master. Other than SOA, you also need NS and A at the minimum.
>> I registered our static IP as NS1.domain.com
NS for domain.com should be pointed to ns1.domain.com. Your SOA should point to ns1.domain.com as well. In addition, you need to set an A record, that's to point ns1.domain.com to your static IP. For your other FQDNs like server.domain.com and fwd.domain.com just need A record and point them to the same IP. If you need to setup MX, set domain.com to point to ns1.domain.com (not mail.domain.com).