(With regards to the people who just want the infinite unit cap and not the 1 sec 1 credit mods)

To everyone on this thread who can see this comment, I have figured out how to make the population cap near infinite (can't find the population limit for certain space and land heroes or the supremacy spawner, so i apologize for that).

However, I don't know how to use the steam EAW workshop uploader so I'm explaining it here instead of uploading a submod.

Process:
First install or find the original unedited Fall of The Republic Mod and go into File Explorer. Once in file explorer go to This PC> Windows (C:)> program files x86> steam> steamapps> workshop> content> 32470> 1976399102> data> XML> Units

Once in Units, open any or all the unit XML files with notepad (or any other kind of word editor you use) associated with whichever faction you like (or all of them), and try to find the string of code that says 'Population_Value'. Population value is the pop cap for each unit deployed in both space and land combat. Simply find the number wedged in between the 2 arrows (exp: >10<) and change the value to 0 (Zero) and the unit(s) you choose in game will cost no population.

Certain units that share the same unit model will also automatically change the pop cap of that unit as well, so you won't always have to sift through and change every unit's pop cap. However not all units are located in the same XML files so it may also take a while for you to change everything. Other than that, you should be good to go.
Hope this helps ~ SuperBansheeUSA