07 silverado Cammed?
 

What does this mean? How will it effect my trucks performance? Is it worth it for the long run? Any change in mpg?

A cam is worth a good bit of hp/tq. Will boost your numbers up pretty significantly with the supporting mods like headers, stall and a custom tune. I'd do it for sure, loved my bro's cammed tahoe he had. and mpg will suffer, but mostly because you'll be into it more driving around town.

Ok, how about the longevity of the motor? Will it still last 150K miles or more? I have heard that they have a rough idle, will that affect anything?

not to jack your thread but iv also wondered about a cam. what exactly is it and will it decrease mpg because il be on the gas more or is that a side affect?

If you're not rompin on it at every corner then it'll last no problem. All about how you drive it. And they idle rougher, but that also can be tamed in the tune and with your cam selection.

Yes just cuse you're on the gas more, long trips it could actually help givin a good tune