i have some questions about my swap

[1970 C10 MJW]

I have a few questions...
1) if i am not mistaken the ecm (99 silverado 4.8l 4l60e) the ecm provides the ground for the fuel pump ground, I have not gotten a tune, but the ecm will not turn the fuel pump on, i manually provided a ground to the pin my ecm is using and it came on. so my wiring is good.
2) according to lt1 swap.com the pinout says the ecm can run up to two fans, those two pins on the ecm also are providing a ground if i am correct. How do I tune this function in? (i am not a tuner i just want to know so i can discuss it with my tuner hes never tuned a gm car, but he is an experienced tuner we will use hp tuners)
3) on lt1swap.com it says we can use a pin for a tow haul mode
A)is this something that can be used with a toggle switch to run a totally differnt tune (for example a 91 octane tune and a E85 tune for the other) or is it only capable of slight adjustments to shift points etc like the factory does
B) what would be required to tune this in
4) what do i need to do with the TCC pin on the ecm? i have put the newer brake swith that has 4 pins (i believe) the two pins for the brake lights and two other pins
5) the tach output pin, I have an older sun 8k tach, what do i need to do with the one pin that i have on the ecm?
I may have more questions... but im not by the truck so i dont remember anything else atm. thanks for any input