I am considering getting a shotgun to add to my small, but growing, collection of firearms. I literally have never fired a shotgun before, so I am treading into new water here. What might be a good starting point for something that would be used for primarily fun, kept for home defense, and could possibly become a hunting platform should I decide I have the nads to hunt?

I might be asking to too much here from a single firearm, but maybe there are options out there. I definitely lean toward the tacticool look, I'm willing to admit, but am looking to learn. Is there a decent entry level model that would allow for different stocks and barrels that could suit my whims? What about semiauto configurations, or is that a stupid route to go for a first shotgun? Something that could (emphasis on COULD since I have no plans to do it yet) be used in 3-gun? The Mossberg 500 seems popular, not sure how suitable it is as a starting point. Feedback is appreciated!

Cheers,
Jamie