I Have a couch I put wheels on, so I can travel down the street to the parade route and to the neighborhood bonfires.
It is great, load all your stuff on to it like a wagon and just pull it along.
Now I have done some more work on the couch, The Getto couch, it has the midwest version of a getto blaster in it. Also a cooler.
There is also cup holders, the instructable is here http://www.instructables.com/id/Pvc-Cup-Holder-1/
It is simple to do, but would be highly specific to the setup on your couch.
There are many instructibles on wiring up a radio so I won't go into that.
Here are some Pictures of mine, this will help you get thinking about yours.
On my couch I have castor wheels on one side and larger ones on the other side, see picture 1
I also put a eye bolt on the leading edge, to use as a lift handle, tow point (tow behind my scooter or bike), attach dog to.
Just screws and bolts hold on the wheels but they have lasted 2 full summers going into the third.
I picked up a pair of speakers at garage sale for 8 bucks, cut up some plywood, to fit the sides, put hole in each, some blocking, and mounted it to the sides of the couch, i cut a slit under the couch to slide the plywood though, cut a hole in the side though the cloth and then stapled it to the ply wood and then mounted the speakers to the ply wood.
A friend gave me a old car radio (no wire harness), I went and mounted it to the front of the couch, got the 12 volt power wheel battery out, found the pin outs, could not get the radio to come on (was in his basement for a while), then in the process of trying other pins I made the majic blue smoke come out of the radio. So i will have to find a diffrent one. I still have to mount the battery . When i get a new radio i will wire it all in with a power switch.
Then I wanted to put in a cooler, the one in used will hold a six pack and ice. Enough for a 2 hr parade. All i had to do was move 2 braces, I drilled out the rivits, cut a hole in the cloth under the cushion, but 2 wood braces and stapled the cloth/padding to the braces. Now the cooler just sit in the hole, and you dont even feel it. It can come out the top. I did not have a lot of room to add this and I did not want to Build a cooler, I should be happy with this. If not I will rework it.