Next update will allow demolishing relays, hubs and settlements. Entering a new map will not be reversible but there will be a better warning about it.
Does it freeze your resource gathering development when you change maps or do they give you a baseline as a starting point for the next map?
I ask you because I am wondering if I change the map too early, will I get slower than if I developed more before changing? Because this is the impression that it gives.
It's currently a bit on the optimistic side, assuming you mine all planets permanently with one extraction drone (taking into account drone module upgrades). You receive an averaged rate of resources in the next mode calculated from that assumption. So if you upgraded the ships more you will have more resources in the next mode.