Using the colors shouldn't be a big deal, they sell team color paint at the store, and displaying merchandise shouldn't be an issue. As long as you're not reproducing any logos or imagery I can't think of any issues. I have tons of hawk stuff around my desk at work, it wouldn't technically be any different to display merchandise anywhere else.
What your issue might be is the associating you're implying, it's sort of a grey area in copyright law and while the NFL may have guidelines, it's going to come down to infringement based on the likelyhood that you're implying some sort of relationship between your company and the team.
So what you need to ask yourself is:
could the NFL/Seahawks possibly be harmed by being associated with my company?
could my company possibly financially benefit from an implied relationship with the team/NFL?
Unless the NFL can somehow prove that either of these cases are significantly true, the worst thing that will happen is that you'll get a request to change things. Even that is a long shot though.
Just make sure that any other branding of your company, outside of the colors, can't possibly be Seahawks related and you should be fine. If you're talking about a restaurant or bar just make sure that the name and any marketing is not likely to imply any association or partnership with the team.
unoffical self-proclaimed .net smartass