Extending sink drains and water lines

[biglott]

Hello,
I need to have my water lines extended to the back of my cabinet. Am I allowed to do this inside of the cabinet, or will i need take up the flooring and do under the cabinet.
If inside of cabinet, I was planning on using 90 degree elbow bend support to the turn the pex. I would only need one connection, plus shut off Valves.

Also my stand pipe is to short, can I extend it with a pvc coupling or should I use the rubber one.

I'm planning on using this design for my drain layout. Is there a minimum distance between the arm and the air and admittance valve.

Thanks in advance for your help, it's greatly appreciated.

 

[Twowaxhack]

Ok on the water lines. Personally I don’t like those bend supports and would rather have 90’s.

If I install a toot vent I try to install it as high as possible and still allow me to remove and install a new one without citing the pipe.