does that mean that the temp sensor on my prins vap is measuring gas temperature ?
No. It is safe to unscrew it, so you can see it is poking in the water jacket. It won't give any useful guide to gas temperature, it used for changeover control (something else the MS can't do as standard). You won't need that at all if you are making a gas-only car.
A real Prins system has temp (and pressure) sensing built into a vapour filter housing.
re referencing the gas pressure to map, there appears to be a pressure referencing input stub on the vapouriser
No, that is a PRV - a safety valve. You can
plumb that into the manifold, or plumb it down to the fresh air, or leave open - just so long as any gas vented under fault conditions (a frozen vap, say) gets dumped somewhere safe.
Unless you've chanced on an already modified unit, which it doesn't look like, the pressure reference on yours takes the form of a pinhole near the adjuster. You need to block that off - I wind in a self-tapper in a blob of araldite, and cut off flush. Then drill a new hole and fit nipple in the 'slopey shoulder' of the central boss. You need to strip the vap or the diaphragm will be ruined.
It's stupid not to fit a new rubbers kit while its in bits.
Occasionally the screws seize and shear, and the unit may become scrap. That one is quite elderly from the label, so it is a real risk.