Playing around with 2800

So I just bought a DXP2800 and was tentatively setting it up. I'm still waiting for my hard drives to arrive next week. In the meantime, I threw a couple of old 1TB HDDs into the bays just to play with it. So far, everything is great.

My question is: What happens when I yank those old drives and put in the new ones? I don't care about the data on the old drives - it's just duplicate stuff I put on to test the NAS. I am not going to copy any data from the old drives to the new ones.

Does all the system config reside in memory (RAM?) or is it put onto a HD partition and gets lost when I swap? I don't have any SSD sticks installed yet.

What about if I install Docker and Plex now. Does that get lost when switching out drives? Obviously, any library would be lost, but that doesn't matter.

Finally, should I just do a factory reset when I get the new drives to make sure everything is starting over fresh?