Not sure of the question numbering system here, but anyway...
3 - If you remove custom sliders and load a game where sims had them in use, they should still appear the same in regular play mode as if the sliders were still there. But if you bring these sims into any form of CAS, the slider info will be undefined and things related to that slider will snap back to 0 and stay there.
4 - The Resource.cfg file can be edited to allow for deeper subfolder nesting than 4 or 5 levels if desired, but doing so tends to have a negative impact on the time it takes the game to startup.
