Basement DWV OK?

Haven't done this yet, but planning it. The pic shows an "x-ray" view of below-the-walkout-basement-slab drain and waste lines.

The 4" main at the R in the pic takes a 90 to run over and pick up a basement bath and laundry washer box.

The washer box is at the far L, and the 2" line coming up is vented with an in-the-box AAV. That 2" line runs over and picks up the trap arm of a tub-shower (trap not shown), which is vented a little ways down the arm with a rolled up san-t going to a 1.5" vent.

Behind that, you can see what happens along the run of 4" than comes off the end of the main. The end is a WC, a little down the line is a san-t rolled up with a 2" vent going up, and the lav sink is adjacent, revented up to the 2".

The stacks at the R going into the straight main are bringing down waste from a bath above.

If there is something wrong with this scheme, please let me know, as work (new construction) is planned to begin soon.

piping

using your drawing, the drain and vent for the lavatory seem to be redundant. I would not use an AAV at the washer, although if the main line is such that it could never plug up and fill with water, you could get by with it.

Here. I rotated the model so you can see a little better.

How is the lav drain, with the re-vent going up and over to the 2" vent coming off the 4" below the toilet, redundant?

Is the revent not needed? If the lav just drains to a 2" stack coming out of the 4" sewer line, is that all that is needed? I'm confused.

Not being a plumber, this stuff bewilders me, but I want to understand it.