I can't address all your questions but regarding the loss of muscle strength on the side where a neck dissection was performed. I recently had a left neck node dissection and had loss of strength and mobility in that shoulder but PT (physical therapy) did wonders and I had in 4 to 5 weeks regained all strength and mobility. Now you mention about the fluid in you arm, I believe. This is probably lymphadema. Because you have lost a large part of the drainage system any injury etc. can easily cause a build up of fluid in the arms particulary. This should be addressed ASAP to get the best results as I was told by a PT who specializes in lymphadema patients. Also, you have to allow yourself time to recuperate, having two operations within a short period of time and to the extent you mention takes time for your body etc. to heal. Hope this info helps!