For the sake of your fish, I certainly hope so!
The only tanks I have switched back and forth between freshwater and saltwater is my biocube, which is relativley easy to do with a few quick rinses and new filter media, substrate, decor and bioballs, and a 10 gallon tank which I used as a q-tank, which was also pretty easy, just a few rinses of the tank, new substrate, decor and filter media for the HOB filter I was using. Otherwise, I am not sure how hard it really should be above and beyond that. Obviously the salt needs to be removed, which can be done with some good rinsing. I have tried to stay away from using any soap and I use brand new, chemical free 'scrubby pads' that I find at Walmart to do any of the tough areas. In fact, if you can't be sure if the scrubby pad is chemical free, I see them being sold as 'algae pads' at a few of my LFS.
For sand, I agree, play sand is a good choice; I have used it once. I have also found some black sand being sold at Home Depot near where they keep the mason sand and such. My brother uses a medium-fine silica sand (sand blasting sand) without problems in his cichlid tank and I think his planted tank even. So, I guess there are quite a few viable options...just be sure that whatever the sand is comprised of is not something which would change your water chemistry negatively and clean it well so that you are not adding anything you dont want to be, not to mention, so that it is easier to deal with. Of course, extremely fine sand is going to be easier to 'kick up' by you or your fish which could cloud the water from time to time, so that is something to consider as well.
Re: Salt To Fresh 
ong the filter wouldnt come back online b/c of the up and down of the volteg from the generater so i lost the fish and let the tank sit for over a year. last week i got boared and decided to make it a fresh water riverbed style tank. so i empty out the salt water w/ pitchers and tock out alll of the gray and disgusting sand. i blasted it with a hose and then used some scrub soft on the sides and botum. and well it tock the better half of the day but i got to fill the tank but first i tock my hanging empored filter and filled it with pure water and put the intake in a cup of pure water and let it run till it was clean. so i cover the botom or the tank with a mix of small and larger pebbles and then pour a layer of playbox sand on top of it and it looks great and works as a natual filter so yeah hope it helped. and now iv got 12 fish in their less then 6 days after i started it. oh yeah im that good well i hope i helped if u got any questions just comtact me and ill see what i can do. thanks for ur time 
