Plumbing - Does this look right?

A friend of mine has taken pity on me and sent me this layout. But I'm wondering about this, it's just to simple looking. Is this correct? His draft doesn't show the drain line going to the septic, it's on the back side. Anyway, I'm trying really hard to learn all this stuff.

Piping

Looks fine to me. The only thing that I would question is if that is the main stack where it is reduced to 2in., thats a no-no, must be full size through the roof or tie into a full size that already goes through the roof. Lots of luck.

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"If you don't have the time to do it right, where will you get the time to do it over?"

layout

I do not know any plumber who would install it like that.
1. There is no legal fitting that could have the pipe to the septic tank going out the rear of it, at least not the way it is shown.
2. There is no reason to have that riser pipe at the left end. It could extend from any of the other three risers.
3. It has to be full size out the roof, and possibly increased in size depending on where you live.
4.There are much simpler ways to make your layout.

New Layout

HJ, took your advice and redid the drawing. Am I getting close?

pipes

Closer. Use a 3 x 3 x3 x 2 side inlet tee at the toilet. Run the shower/tub into that without a vent. Put a tee in the toilet's vent riser and arm over to the lavatory with an elbow at the end of it, again without a vent.

Lets see how I did

I hope I understood you correctly HJ.... here's what I have so far... The way it sounds, I don't have a vent.... I must have misunderstood you.