Yes you will have to have the PCM reprogrammed if you are going to do it the right way. Im my opinion Comp Cams has the most experience with LS1 cams you should give them a look. The LS6 cam is popular and produces good results for most people. As for the rocker arms, you need to pay attention to the ratio vs your lift. If you get a high lift cam stay away from anything greater than 1:6.

Long tubes are harder to get passed emissions unless they are coated. This will help keep the cats lit and helps scavenging.

Selecting a cam is like a sience. You need to account for things like gear rations, stall speeds, etc. Bigger is not necessarily better. I have a post somewhere on this board where I explain a little bit about cam specs. Give it a read. I will try to search for it and post the link here.

Good luck!