I've got a v 1.0.2 iPhone with an ATT SIM in it that has been jailbroken and apps installed. This phone has NOT been unlocked. The SIM came from my blackberry, which I'm going to retire and switch permanently to the iphone. Since the BB unlimited data is $45 and the iPhone data plan is $20, I figured I'd "go legit" on the activation on the phone.

So, now what do i do so that I can walk into the ATT store and activate my iphone as if it were new?

I was planning on doing a restore of 1.0.2 and then put the original ATT SIM into the phone, then do the activation and all will be good, right? I'm not thinking that I have to "revirginize" the phone, correct? Anything else I have to look out for since I'm sure that iTunes will want to push me up to 1.1.1 once I'm activated, which shouldn't be a problem.

I'd also like to install some of the apps that I have installed once I'm done and activated. I'm assuming jailbreaking and doing that is pretty much the same and that I can use iNdependence to do this?

yes, you should face no problems.
you can simply update to 1.1.1 and then activate
follow that by checking the unlocking section for the simplest jailbreaking method (by visting jailbreakme on your iphone)