That all sounds about right. With the exception of mounting it in the tyrewell? Do you mean on the inside of the boot or the outside? FYI, it is illegal to have it in the boot.
The current in-tank pump will be fine as the low pressure one and a VL turbo, or equivalent should be fine.
Yes, you can wire them in parallel, but if you do this, remember if one pump goes, it is not going to stop the other pump. so you will either run out of fuel or the surge tank will overflow into the tank over and over again.
Also remeber when you first install it, leave the VL pump unhooked and prime the in-tank fuel pump (Turn the car to "on") 5-6 times to fill the surge tank, then hook up the VL pump and off you go.