Talk Me Into Using Megasquirt?

I used several different ecu's to tune my own fox Mustangs (A9L, X3Z, CBAZA for a 2.3L n/a, to name a few), with either TwEECer or Moates QH. I don't mind using these moving forward, but since I will be tuning both a v8 and a 4 cylinder in the near future (hopefully), it will benefit me to have these 2 cars be as similar as possible.
I like Megasquirt because of price, and from what I understand, system flexibility (I have questions below on this however).
What I don't like about megasquirt is trying to figure out the differences between systems. There isn't a really good detailed technical spec sheet/comparison between the MS1/MS2/MS3. It is all written as hi-level advertising... I think I am figuring out what I need to know though, it's just slower than I had hoped.

My background: I work in Materials/structural test for a commercial aircraft manufacturer. I have written several versions of software applications for thermal control (PID based), data analysis/reporting, and monitoring of test rig activity. I have tuned my own 408w as well as an N/A 2.3 running at first on a CBAZA ecu, but later switched to CZAJL (both are v8 ecu's). I messed around with Arduino stuff as well, but nothing more than exploring/playing.
I don't mind writing my own code, calibrating sensors, etc, as long as I don't have to use Ladder Logic. That is part of the fun of messing with control systems

So, that was long-winded... here are the questions I have right now...
Can I customize inputs to fuel and timing? For example, could I average 2 intake temperature inputs to correct fuel, instead of basing fuel adjustments on a single temperature input?
Can I create my own code for something like a fan controller, using a PWM for variable fan speed, and switch to relay control when desired (programmatically)? I would otherwise build this with Arduino, but would prefer it integrated with the ECU.
Could unused Fuel injector outputs be repurposed? Can the output hardware/channel be reprogrammed by the user? In other words, .if using an MS3 on a 4-cyl car, could I use the other 4 injector channels for control of electric water pump/fan? Can I write my own code for control of these channels? If so, what programming language would be used?
When using the GPIO kit for output control, what programming language is used?

It will likely be some version of MS, but haven't had a chance to firm up plans... Kids have me running pretty hard these days.
The QH has worked well for me in the past, but the cost of the software keeps going up. It isn't overpriced, but I seem to lose/kill laptops often enough that repurchasing software irritates me.

I could probably sell most of my factory ecu's and tuning gear to cover the cost of the MS system...

Rt jam said:

Is sequential important to you?

Click to expand...

A little slow getting back, but yes, I do want sequential fuel.

Life has been a significant distraction from my car hobby, but should be settling down soon.
Here is what I am thinking about for a shopping list...

MS3 - $509 - https://www.diyautotune.com/product/ms330-k-kit-with-mapdaddy4-upgrade/
GPIO Kit - $278 - https://www.diyautotune.com/product/gpio-basic-kit-black-case/
Software Kit - $23 - https://www.diyautotune.com/product/usb-to-serial-adapter-works-with-tunerstudio/
MS3X Kit - $111 - https://www.diyautotune.com/product/usb-to-serial-adapter-works-with-tunerstudio/

Total $921
Am I missing anything that would be needed to run a 2.3 n/a engine?
I know most of this stuff is overkill, but I am looking for expand-ability and do not ever want to hit a hardware limitation when making changes in the future.

Might be able to start collecting hardware in a month or so...