Hi GPMX, I,m new to this electronic tuning thing, and would appresiate some help with regard to different PCM,s

I am busy with a project vehicle that I have built up from nothing. The vehicle is a Nissan 4x4 UTE that I have put a LS1,4L65e and NP205 transfer box into. The engine is a stock 5.7 bottom end with LS2 heads and intake manifold and an LS HOT CAM.

I have a stand alone wiring loom from LT1 conversions, that will accept a 12200411 ECU. The ECU plugs are Blue & Red on the loom. I have a Roadrunner ECU that uses the Green & Blue plugs,
Question 1: are the pin outs the same for the different colour plugs (can I just change the plastic cover and fit)?
Question 2: can I download a 512k tune to my 1024k RR ECU or must it be form a 1024k ECU as well?
Question 3: what OS should I be looking for?
Question 4: where do you think I can find a basic tune for my application

Thanks in advance for any help you can offer, I live in Cape Town, South Africa and I am unable to find any one here with any experiance with regard to EFI, so I'm on my own here.