Need Advise on Drain/Vent Pipes

I am in turning an old house in 2 apartments. I completely gutted the entire house and i am no novice plumber looking for some help/advice. Please take a look at the folllowing PDF files that have my pictures and comments and let me know your thoughts. I have a few questions and please also add any of your comments. Thanks.

http://www.vertaxllc.com/plumbing1.pdf

http://www.vertaxllc.com/plumbing2.pdf

1. Can i vent the tub the way i did?
2. How should i connect the toilet, the 2" line from tub/sinks, to main stack... and vent properly?
3. Does my sink/vanity drain pipe look ok?
4. Does it meet code?
5. Can i have the 2" vent from the tub/sinks meet up with the 2" vent from the main stack and increase the pipe size to 3" before it exits the roof and take it 3" thru roof?
6. Do i need any additional cleanouts?

The first thing I see is that the sink drain and vents are wrong.

Most simply stated, the length from the trap wier to the vent cannot exceed 1/4" per foot of pitch or you risk siphoning the trap.

A kitchen sink drain should be 2".

If you try to run a snake down your sink it will come up in the other sink. That should be a double fixture fitting, not a double sanitary tee.

The lavatory would be "s" trapped. I would have wet vented the kitchen sink with the lavatory.

The waste/overflow looks jacked up.....it's not installed properly. Leans toward the tub like the shoe assembly was not cut to fit.

You can't wet vent kitchen sinks, only bathroom fixtures. You could waste stack vent it though by increasing the drain to 3" and 13' or less.

That's from a guy that has been working in the field for over 38 years now, not an internet plumber.