Hi Illyria! Thanks for taking the time to post your suggestion! These sorts of posts are my favorite to read, because they always have valuable insight on the real world use of my mod (since I don't get to play very much anymore).
Sorry for the delay in replying, they've got me working a ton of hours lately. As for your suggestions...
1.) Cartridges as condensed ammunition repositories to make loading more efficient, rather than more difficult.
A.) This is an excellent idea! I recall there is another mod that does this exclusively, but having it as a feature in my mod does make a ton of sense. It would be another optional logistics puzzle the player could implement as they acquired more expendable resources (probably mid game and later). If I did this, I would integrate cartridges into the main body of the mod and eliminate the "hard mode" entirely.
Cartridges were originally intended as a way to balance the utility of the loader chests against vanilla logistic requirements. I believe they pretty well fail in that regard, as they provide no logistic puzzle and only increase resource usage. Something like this could make use of the whole cartridge system in a much more interesting way.
2.) Loader Chests using fuel/energy.
A.) This is a great idea for mod balance! Actually, this is something I've already got in development. I toyed with this idea in a separate branch of the mod, and I was pleased with the results in play testing. Now, I am just trying to figure out the best system to use (electric, fuel, or a separate ammo the chests would use) that would provide good balance. I plan to implement and release this along with the range extender idea that another user proposed to me. Development is taking longer than I'd like due to my increased hours at work, but look for this in the near future!
As always, thanks for using my mod and posting your suggestions. It really does help me in mod development, not to mention that I simply love to hear from people who use the mod. If you have any other suggestions, don't hesitate to post them!