You can install an underfloor heating system which is a series of pipes running under the floor where hot water runs and creates a warm floor and also heats the room with radiant heat. This is actually the most effective form of heating a space and is the most comfortable. The system components can be purchased or you can have a licensed contractor install it for you. You can put just about any type of flooring over the top......tile, laminate wood,........ Regarding flooring, if it is a very wet bathroom, I would prefer tile, but if will not get a lot of moisture you can use wood or laminate flooring.

Could you look at separating walls between the two? What else do you want to put in the bathroom? Probably the best type of tile is a white ceramic tile to blend the floor toilet with the floor. Do users have good vision (not elderly) as if there is a problem of using the floor toilet in the night, you might need a darker tile to delineate the floor toilet

Area 6'x7' requirements:- basin, W.C., steam bath

sorry to say but your plan is not showing in your post. Anyways please upload your plan and the main outlets of the bathroom, so that it will be easy for the perfect planning.