Air pressure: any sensor that's suitable for this pressure level.
Inlet/outlet valves: easiest is a solenoid valve, again use one that can handle this pressure level, and also one that's of the correct size for the desired amount of air flow.
For the valves I recommend you to go for a DC version, 5-24V, as that's easiest to control and safest to work with. Can just use a MOSFET driver for that. AC is much harder to deal with.
Since you are monitoring "air pressure" is it correct that the gas is ordinary air?
It looks like you already have the equipment and that you are trying to automate an existing manual process?
You might want to check how hot and cold the inlet and outlet get during normal use just to be sure any valves you buy will operate within specification.