Roughed In Bathroom - Basement

I am finishing off my basement. It appears the previous owner was planning to put a bathroom in the basement. I want to add the bathroom, but need to defer it until a later date (due to financial reasons). I need to frame out the bathroom walls now so I can finish the rest of the basement (ie floor, ceiling). I am trying to minimize the amount of work I have to redo later (when I add the bathroom). The problem is, I am not sure what I am looking at. I plan to hire a professional when its time. I dont want to call a plumber out now and waste his time when I dont plan to do it for another year. There appears to be (a) drain (floor to ceiling) - qty 1 (b) vent (floor to ceiling) - qty 1 (c) round metal plate flush with the concrete floor - probably the set up for a toilet flange (d) a drain in the floor, below the concrete. It looks like they cut a section of concrete out (~1' x 1') and there is a drain capped off that continues to go under the floor (horizontal). I assume that is for a shower???

Any input or direction on where I can do more research is appreciated. My immediate goaln is to frame the walls so I can finish the rest of the basement and not to have to move them a year from now (when the plumber shakes his head and wonders what the heck I was thinking).

Thanks