Help me identify my rough in plumbing pipes

If the basement bathroom requires a sewage pump, one of those pipes (quite possibly #3) will be the output of the sewage pump going up to the level of the house drain (which is presumably above the floor level, if a sewage pump pit was roughed in.) Pull the cover off the pit and poke a snake into the pipes...

Or if there's only one pipe into the pit, and the pump output would go out via the cover, it may be a vent pipe and cleanout access.

Lack of vent pipes above the concrete is fairly normal. The rough in is "put pipes before pouring concrete" rather than "prepare all for a bathroom that hasn't been put in for the next 11 years, and may never be" - pipes above the concrete are easier to add than those below.

Sump basins are pretty generic - make sure the pump you want to buy fits in the one you have, but that's pretty much physical size of pump and hole, not brand-specific. The part number is for exactly what it is - a sump cover. There will be a sump basin under it, with the plumbing run to it if it's in fact for a sewage pump. An alternate possibility (not knowing where your sewage or septic pipe leaves your house) is that the sump cover is covering "the other kind of sump" (drainage) and the bathroom plumbing goes directly to your septic or sewer pipe below floor level. Once again suggesting open it, take a look, poke a snake in the pipes and see where it comes out, or listen for it, anyway.

You don't give a close up for #1 so I'm not sure what it is. If I were to guess #3 is the toilet, and #5 is the tub/shower with #4 being the vent for the shower drain (it could also be used as a "wet vent" and be the sink drain.) They expect you to build out a wall off the basement wall to allow for insulation, which is why those pipes are so far away from the wall.

#1 may be a below slab vent for a future radon system.

The pit and #1 are expected to be outside the boundaries of the bathroom, another wall would be build behind the toilet separating it from the ejector pit and #1. As you enter the door (on the bottom between #3 and the future wall) the bathtub would be on you right, the toilet on your left and the sink on the left near the far wall). The ejector pit will need a macerating pump and lines run to vent and the main sewer.

Ultimately the best best is pay a plumber for an hour of time with a camera snake and a tracer. It will let you figure out exactly what the original plan was.r