When I shutdown NIS while having NCC open with me being logged into my wallet and then start NIS again I get this message. Shouldn't it start automatically even if I just restarts NIS?
NIS needs to be booted. Please open your wallet and boot a local node via the popup dialog or configure the auto-boot setting. (at block 3663)
Start =/= boot
If you let NCC open and stay logged into your wallet and then restart NIS, you have to boot it manually. Take a look in the menu on the top right (arrow down symbol) -> "Boot Local Node".
What does the "block difficulty" really mean? Does it depend on "how much importance" that is currently harvesting?