Didnt' realise you were also part of the eastside crew!
I haven't been to many meets to due rolling weekend commitments and now i'm selling the Mustang, but i might go still to some in the future using the replacement
Get something like the CTek MX 5.0
You can buy an attachment that will plug into the 12v port (aka cigarette lighter). However, i wouldn't recommend it, sticking the stock eyelets on the battery terminal is better since it's direct, it's easy to charge thereafter, and you can keep car locked...
I wonder if it was the ambient air sensor? Mines effed. Doesn't read properly, could be 20*c outside but it reads 45*c. I believe it can play some role in the aircon too...though perhaps maybe that's only when the 'auto' setting is used...
Any chance they gave you paperwork that says the part...
Correct you need the HS/MS switching, though some units do it automatically i've heard.
I did mine via PC without issues (also wired rather than wireless). But it's a fiddly SOB that's for sure.
It's also supercharged (Whipple), different rims etc too.
They're all sold out FYI but you can have a read here https://www.carsales.com.au/editorial/details/exclusive-635kw-ford-mustang-special-revealed-121518/
Sent me an updated file but i haven't had a chance to play around with it. I've left it on the original Lund and honestly i'm so over it that i'm likely to just go stock tune bc the throttle makes the car feel like a pig.