For hostgroups you need to extend the cmcdump that it also outputs the existing hostgroups in a way you can use on the central server. I think this is not so easy.
The folder problem should be not so complicated.
Inside the cmcdump data you have all the custom variables and they also contain the folder where the host “lives” on the source machine. If the same folder exists on your central system, then you should see the remote host inside this folder on the central system.