I long ago altered my data set to make more use of the other two resources. I have Facilities costing FAR more in the Organics department to simulate the need for people and infrastructure. Engines, Missiles, Fighters and many weapons require more Radioactives in my set, giving them a higher upkeep cost in that department. Many facilities also require more in the way of Radioactives and refined goods in my set.
So overall, I have it set so that mass colonization require larger amounts of organics and radioactives. Mass ship building still requires minerals, but the other two are still necessary for long term maintenance.
Also, to facilitate an increased need for these two resources, I greatly reduced the amounts that Farms and Refineries produce. Thus, you have to make more of an investment in them to get the resouces. It works pretty well and I'm pleased with the effects its had in my game. The resources are all important, but for different reasons and at different stages of the game.
Of course this entailed a reworking of the AI's colonies and colony type. Obviously the default settings for them left them with far too few of the latter 2 resource type. I've slowly been tweaking the AI in this regard and it runs a reasonably well-balanced econ at this point. Of course some of its colony decisions are atrocious, but this is beyond the control of what we have to work with, I believe.
One thing I would be hesitant about is the food required/pop thing, for a few reasons.
1) I dont really want to see a return to the MOO model of 'feed your empire'. IMO, its not something that interstellar empires and emperors should be concerned with. Heck, the percentage of people working in food production has been steadily declining in our world as technology increases. IMO, it will be largely a non-issue by the tech levels the game postulates..
2) Population is not really that worthwhile as it is right now in the basic game. Whether or not a colony has 1m or 1000m is largely immaterial IMO. The production bonus is nice, but not make or break. So 'charging' people for their pop seems like a bad idea and one that will encourage people to NOT want to grown their Pop. Thats just my gut feeling, but unless/until pop REALLY means something (like in MOO), having a 'pop-upkeep' sounds like a bad idea to me.
Just my $.02
Talenn