you dont need a skimmer, certainly you can wait on that for a bit...
you also dont need a 'bubble wall' or other bubble generator... again, this is a fresh water thing...
As for ghost feeding... this is something that some folks will do to help cycle thier tank... chances are, your tank is already cyceld since it has been up and running for a bit... if anything, it has a minimal biological filtration...
The cannister filter, is probably not needed either, but since you have it, might as well use it but it will only serve as a 'mechanical' filter... it will catch the food particles and other chunks that are in the water column...
again, this isnt really 'needed'.. the 'chunks' will settle out of the water without the cannister filter...
also, the cannister filter, if you dont clean it often, will keep that trapped food and other junk in the water column.. it has no way of removing it on it's own
the natural filter/biological filter does have a way of dealing with toxins and junk, which is why the LIVE FILTERTRATION is vital...
please do some ammonia tests and nitrite tests and salinity/pH and let us know...
thanks
b