Server's Hostname/nameservers Affect Mail Delivery

our company is ordering a new dedicated server and we are a little unsure what we should choose as far as the full hostname and nameservers of this one server.

This server will have a couple different websites on it, but really, there is only one BIG website on it... let's call it abcd.com.

While most would pick a hostname of host.abcd.com for instance, if at all possible, we would like the domain name part of the hostname to be something different than abcd.com. We own a domain name that doesn't point to anything yet (unuseddomain.com) and we were wondering if we could use that domain in our hostname.. host.unuseddomain.com.

And instead of using abcd.com as the domain name for our own nameservers (ie. ns1.abcd.com, ns2.abcd.com), we would like to again, use the unused domain name we own (unuseddomain.com) for the nameservers domain name: ns1.unuseddomain.com, ns2.unuseddomain.com.

So...

Will this work? Is this perfectly acceptable?

And lastly...

Since the one website we really care about on this server (the one we got the server for in the first place) is abcd.com, is using the unuseddomain.com for the hostname and nameservers (as above) a bad choice in anyway regarding email deliverability? I understand that mail ISP's (hotmail, yahoo, etc.) do all kinds of checks on hostnames (PTR), etc... and we want to make sure that we aren't hurting ourselves in anyway by using an "empty" domain name that we own as our hostname's and nameserver's domain name.

For instance, if we send mail from the abcd.com account, it will use mail.abcd.com (1.1.1.1) as it's outgoing mail server... Hotmail will see this... do a reverse-dns lookup on 1.1.1.1 and see host.unuseddomain.com. See what I'm saying? It all will work, but will it toss up red flags?