basement plumbing rough-in

hi,

my bathroom in my basement is roughed in with plumbing. there are three pipes. one that is obviously for the toilet, one that sticks about 14 inches out of the concrete floor, and then one that runs vertical along the wall of the concrete to the left of the toilet. this pipe that runs along the wall and down into the concrete also looks as if it is vented as the pvc also goes up and into the i-joist. my question is which pipe is for what?

the tall pipe sticking out about 14 inches is for the shower right?
the one that is in the wall and drains down and vents up is for the sink right?

why doesn't the sink just go down like the shower drain?

does it matter which pipe the sink or shower drain into?


also, i replaced my sink and faucet in my kitchen with a sink that only has one drain hole. to get rid of the other drain i simply blocked the old drain's plubming by wrapping the pvc drain pipe with plumbers putty and putting a rubber plug in it. i capped it just above the p-trap so the p-trap is still there think that is ok?

thanks,