no ebay junk! (unless you can find a used one that is not locked up but its a 50/50 shot). Summit racing can be your friend, also find one reading reviews you are interested in then start searching the net for the best deal on one. They will be in the 300-400+ range for a good one that is easy to use. Beware a lot of these make it so you HAVE to use premium only from then on, but there are ones that you can tune to run on 87.
Headers full length, there are others but this was a quick search and cheapest, shortys are even cheaper
this is a very good programmer that i have known a lot of guys to use
Don't get too crazy with the exhaust (size wise), if your looking for torque go 2.5 inch into an x pipe then either dual mufflers or dual in dual out muffler, 3 inch i think is too big for what you have and you'll lose some possible torque gains. BTW: those headers were for your truck in stock form so they should for sure fit if its lifted that much