Basement Bathroom Rough ins?

We have a ten year old house. We're kicking around the idea of finishing the basement DIY. It looks like we have some rough ins for a bathroom but I'm not sure it's a full bath.

There's a 2" pipe that runs to the ceiling, a 3" pipe about 14" from the wall, and a 4" pipe sunk into the ground with what looks like a clean out cap. Can someone help me sort out what the original intent may have been? How much work to make it a full or 3/4 bathroom?

Layout and photos below.

3" pipe with test cap is for WC...
1-1/2" branch off 2" vent/drain is for lav...
4" pipe has go me confused... - don't know - probably EOL Cleanout.

Pic 3 looks like a floor drain with a rag in it but I'm not sure.

Can you post a full pic of the floor?

I'd expect to see (best case) 5 pipes:

2" drain for tub, 2" vent for tub
3-4" drain for toilet, 2" vent for toilet
1.5" drain/vent for sink, running to ceiling

Coupla questions:
1) Where does your main drain line exit the house? Above or below the slab. I assume below bkz you haven't mentioned an ejector pit.
2) Where is the main exit with respect to the stubs you've indicated
3) What size is the drain line coming out of the bottom of your 1st floor toilet?

It would be helpful if you open the 3" and 4" then measure the depth. Any way you can ask the builder or previous owner what those pipes were for? Certainly looks like you can take what you have and make a bath out of it.