Hello,
The mod does not limit the researchable technology. That means you should be able to research from Neolithic to Spacer without any problems.

But there will be some problems...
I don't think you can use Rimedieval to limit enemy factions to the Middle Ages, because I can well imagine that removing Rimedieval can cause problems. That is, while you are in the Middle Ages, factions with modern firearms might attack you.
However, this is all just a guess ;-)... as I only play medieval.

Another problem is that MO changes the resources while the map is being created. For this you can use my mod, Medieval Overhaul: Toggleable Stuff, which reverses this change. This will allow you to find Plasteel and Steel again. But you must have my mod and the appropriate option enabled while a map is being created.

To MO:Royalty. You should be able to remove it without any problems. The only important thing is that you don't have any pawns on your map and that you don't raid an Empire settlement. However, you may get some errors when you load the savegame for the first time.

That is very good, love it that i can progress through on my pace
I might use something like Faction Control or World Edit to spawn factions in their appropriate ages as well, then.
Thank you very much for your help