Quick question about ue5 tips, and DDC, saved folders

I found some ue5 tips and tricks like youtube channel William Fisher or WTF is?
Is there any other channel or list.

Where is the settings for DDC folder save location. City Sample is taking data in the project folder and not in C: drive but other ue5 projects take space in C: drive.
What is in saved and instances folder? Are those deletable? Assume I don’t need quicksave I have some git perforce going on.