Well, sorry I guess at this stage you are asking the questions that are very basic : ), I believe it is best if you start from the beginning and look into the starting tutorials both for maya and unreal concerning this subject before you move on further, to the more complicated tasks, it may be less confusing that way for you and better since explaining those points would be near impossible here.
In short the assets would be in Maya first before UE, at these stages UE is non existent, so you need to set everything up in 3d app first. Mocap and coordination is a subject of its own and requires careful measurement and planning. so if a guy sits on a chair you need to roughly measure the circumference of that chair to somewhat match your 3d chair height size etc…( ex. Royal chair with handles vs bar chair etc…).
Later everything would be assembled in maya. The import into UE4 from Maya for a prebaked scene should come in exactly the same way as you have arranged it in Maya, this is not a problem.
I see so basically everything would be handled like it was a Maya work from the start, UE4 would just be used for its rendering
I guess if thats the case, might as well just go thru the whole thin gin maya if we already got that far, instead of reconfiguring everything over to UE4 and working with SSS and diff shader constraints