@00diabolic
1. No you cannot run atmo/sxos at the same time on both nands if thats what you mean.
It is highly recommended that you have emunand to keep your sysnand clean for online play
So if you want to switch payloads to whatever nand your using you still need to use either hekate or sxos's payload screen to choose.
2. Yes once you have emunand you can do all of the dirty piracy/cheat stuff on it while playing legit on sysnand with no piracy and online play.
3. No hekate menu is basically the same as sxos menu screen they are payloads themselves that let you choose other payloads such as atmosphere primary fusee.
4. No you still need to reboot whether you have emunand or sysnand cfw to choose another payload. I think the confusion is that no one has told you that both sxos and atmosphere are cfw payloads.