Blender to UE4 Workflow for wall meshes

I modeled an interior of a building in high precision (but not very much detail) in Blender and want to import it to UE4.

Should I export the walls and floors all separately to manage collision and applying materials in UE4 better? Or will importing it all as one big mesh work better?

It has all the door and window openings, but no mapping of anything other than normals, and a very low poly count. It’s basically flat walls with holes cut out.

I’ve read the UE4 guides for preparing assets for import. But I couldn’t find anything specifically about walls and floors. They wouldn’t be any different except that when they make up a series of rooms, it’s like being inside an object. I am asking if that causes any problems with collisions, rendering, lighting, having different materials on different surfaces, and so on.

Sorry if it’s a noob question. I did try to find similar questions and couldn’t. -and I’m a noob…