I'm staring a campaign in a post-apocalyptic setting inspired by Warzone 2100 and RIFTS.
Here a more detailed description of the setting:
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It's probably some time between 2050 and 2100. Some decades after a WW3 with generous use of nuclear and chemical weapons nearly all larger cities are completely uninhabitable. We're not sure if we want to have magic at all, but if we have it, its rare and not very powerful (even to the relatively tame standards of games like shadowrun). Most nations, corporations and nearly all global trade ceased to exist and the areas that are still somewhat inhabitable are controlled by local warlords who are in constant turf wars with their neighbours. There's still something left of the larger nations like the US, but they only claim about 1/5 of their former territory and control and inhabit not even half of that. Most of them are isolationist, reactionary and highly religious dictatorships. They preserved or rebuilt much of the old technology (which is a bit more developed than ours, pretty much upper cyberpunk standard), but deny the people access to most of it (there is no such thing as the internet, and most people can't even read or write). These nations forbid the export of technology or resources, making modern equipment, electricity and fossil fuels extremely hard to come by for anyone outside.

I have some questions:
- How far could the tech level of the world (outside the last remaining nations) reasonably drop?
- What equipment (especially weapons and transport) will the warlords probably use? Is it at all feasible to maintain and fuel a few motorized vehicles, or is returning to horseback riding (and walking) the better option?
- Is there any material you'd suggest for information on what life's like in a setting like this?