SAP WM / RF related functionality is flexible to use both on RF device or SAP screen so keeping that in mind i can confirm that you can use the the RF for single process or multiple process or for a specific area. it is not necessary that all warehouse activity should be on RF but from consulting perspective if you are configuring the ITS mobile for single process or multiple process, configuration time remains same, you need to procure and installed the access port in the warehouse for proper coverage.
wrt to example yu mentioned "want to pick SUs that we want moved and then later download the SUs and move them"
The second part of the above statement "download the SUs and move them"" is not clear however regard the first part. if the requirement is to pick the SU and transfer to the line side then it is pretty much possible in RF you can transfer order for the line side and use LM05 /LM07 to perform the confirmation activity using RF
