Revalot

1st serious post after being a member for a few years, anyway I just got my 72 Chevelle started last month(after 468BB/T400) with a LQ4 2005 low mile motor, I put Trailblazer SS stock manifolds and a T56 magnum behind it, S N S performance done my ECM and wiring, now here is my problem. I understand that when you go from LQ4/4L80E to LQ4/T56 the programming has to be changed in the ecm for a manual(idles at 300-400 which is to low, I idled it up by using the gas pedal), do I have to pay 500 bucks( if so I might put a 228 cam in) to do the reprogramming for stock motor? I wanted to break my new transmission in before twisting on it. I know there is a LQ4 NV4500 file, the other thing is I need to reattach my exhaust I cut the collectors about 3 inches below the 02 sensors which can cause I think bad readings while running I know that needs to be fixed asap !(and check all grounds) And some say I need a vss sensor some say you dont does it matter? and I have put a cai kit from spectre 9900 kit on it. Any help or advise would be much appreciated.