2007 Serotta Fierte Ti ; 2003 raleigh m-80 ; 1983 Motobecane Grand Touring (being transformed into Townie)
I'm not the most experienced member on here by a long shot. I'll pass on the advice that I hear often though. I've been advised more and more to upgrade my riding before I look to upgrade parts. Especially if it's a new model that you're happy with, stick with it for awhile. Unless you are doing a riding style that is clearly beyond the ability of this model (for example, a big rider doing major freeriding on a bike that isn't sturdy enough..at which point they should look at another bike). But if the bike fits you and fits your riding, then stick with it.
The most common exceptions to that would be:
seat (not post), if it is really uncomfortable or causes undue pain.
pedals, if they just aren't the riding style that you do or are comfortable with.
aside from that, don't become a weight weenie until there's a good reason to be.
I just got a '05 kona fire mountain whick I am very happy with, but I just has 2 questions.
1. If you guys/gals were to upgrade this bike what would you upgrade and why?
2. Also what is the purpose or benefit of changing/upgrading components like the headset, stem, chain or even the seat post?
Given that you have a brand new Fire Mountain, I have to echo re-cyclers comments. I just got a 2005 Kona Blast and changed the strap pedals to clipless. All other components I will leave as is untli they break.
Given that you chose a Fire Mountain (MSRP 549) and not a Blast (MSRP 699) which is just one notch up was either because of availability or because you wanted to save $150. Any bike you choose to upgrade on your own will likely be more expensive than one you could buy that's higher up.
That's not to say that your idea of switching out components is a bad idea, but you sort of have to plan it carefully. If you end up swapping everything out on your bike and end up with a bike that's spec'ed like a Blast and spent $300 then you have to ask yourself why didn't you get the Blast to begin with.