You'll need a work surface about 4' x 3' to be able to build comfortably. If you're willing to pack things up at the end of each session, you could probably stick it between the bed and the wall. It may be easier to just get an ARF.

Unless you're willing to spend a bit more, I wouldn't get a basic 6-channel. Usually by the time you want the extra channels you want the computer functions, too. People often mention using the extra channels for things like flaps and bomb drops, but those aren't all that common. For sport models flaps are more novelty than useful, and bomb drops can be connected to the rudder channel without too much effort.

The gear inside of the plane is the same whether you go with a 4-channel or 6-channel, so there's no greater expense to crashing associated with a 6-channel. Unless you really put it in, the radio gear usually survives anyway.