Question about interior with Air

hi guys,
i think im gettinga  previa soon, (seeing the car in a few days)
im 100% sure im getting Air,....n interior done...
should i do the interior floor 1st???
or get the air installed, with the tank at the back first??? cuz nvr installed air be4, 
will the tank be bolted to the floor????

is it hard to remove the tank afterwards??!?!!

Wheels and air 1st. In my opinion. .

install the air under the car where the spare tire goes..