Server missing a reverse record pointing back to its host name

I have a dedicated Linux server using Plesk 8.3 through godaddy and am hosting my own nameserver on this machine.  As I am not familiar with nameserver dns requirements, I need an expert's help.  Here is what I've done so far to set up my nameserver and get all my domains to work on it.

What has been done on godaddy's servers under manage domains, not my dedicated server:
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Created ns1.domain.com and pointed it to xxx.xxx.xxx.xxxx
Created ns2.domain.com and pointed it to the same IP... xxx.xxx.xxx.xxx
Set ns1.domain.com and ns2.domain.com as custom nameservers for all my domains

Added these records to domain.com on dedicated server:
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domain.com NS ns1.domain.com
domain.com NS ns2.domain.com
ns1.domain.com A xxx.xxx.xxx.xxx
ns2.domain.com A xxx.xxx.xxx.xxx

Added this to my DNS template so newly created domains will have correct nameserver specified:
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<domain> NS ns1.domain.com
<domain> NS ns2.domain.com


Now for the question:
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1. Is it ok that I am pointing ns1 and ns2 to the same ip address of the dedicated server where domains are hosted?  For some reason I thought that ns1 and ns2 had to have two different ips?
2. This is the main question.  When running a DNS --- Zone Report for any of my hosted domains using the tool at http://www.howismydns.com/tools.php, why do I get the error: "At least one server is missing a reverse record pointing back to its host name...
nameserver: ns1.domain.com, reverse record: ip-xxx-xxx-xxx-xxx.ip.secureserver.net
nameserver: ns2.domain.com, reverse record: ip-xxx-xxx-xxx-xxx.ip.secureserver.net
3. Do you have any other wisdom to share in regards to setting up your own nameserver and does it appear everything else is correct?Start Free Trial