Replumbing a Bath

I've been reading this forum for a while and have found some really helpful advice and a vast amount of knowledge. Drawing on that advice, I have sketched out a design for the plumbing in my bathroom which is going to be remodeled shortly. The toilet and tub will be staying in the same locations. I will be adding a double lav and therefore the location of the existing one will change slightly. I have also attached a photo of the existing lav/toilet/main/vent connection. Some background:

1) Total DFU's on house: 23
2) Main line is 4" Cast Iron
3) Existing vents through roof: 4" for main line/toilet (which I plan to replace with a 3"), 1.5" for shower and tub, 1.5 inch for kitchen.

Basically, I would like to know if the drawings I have attached will fly. Thanks!

You are under UPC plumbing code.

The double lav needs to be a double fixture fitting, and you can use med 90's on the trap arms. Long sweep would work too there.
You do have a long sweep below, and that's correct.

4" allows pretty much as many toilets as you like.

I don't understand how the lav vents are tying in. It should be above 42".

Good plumbing practice would also install a cleanout tee beneath the double fixture fitting.

Thanks for the responses.

1) As far as the long 90's on the lavs. I'm slightly confused by the code -- I thought all horizontal changes of direction had to be "a one-sixteenth (1/16) bend, one-eighth (1/8) bend, or one-sixth (1/6) bend, or other approved fittings of equivalent sweep". Are the 90's on the lavs an exception or am I misreading the code?

2) For the lav vent connection -- sorry, my picture isn't clear. I plan on tieing the lav vent in the third picture into the 3" main vent in the fourth picture well above 42".

3) I thought I read somewhere on the forum that it was bad practice to dump the toilet directly into the main line as I have done. Is that true? And, if so, might there be a workaround you could suggest?

4) I was hoping to avoid a cleanout cover in the wall because the lavs are pedestal sinks, but I guess I could hide the cover with a freestanding storage unit of some sort.

Thanks again for assistance -- it is greatly appreciated.

So, based on further reading here, it looks like the toilet drain set up I had done above was incorrect because other fixtures drained in before the toilet vent. I have attached two different options which I believe fix that problem, and I was wondering if one would be preferred over the other. Thanks!