The valet key will allow entry into the car, which then the floor lever will allow entry into the trunk (even though the valet key doesn't directly open the trunk).
TirePressure.....Each of the 5 tires has a transmitter, which transmits it's 7digit ID# and it's pressure. The TPMS computer monitors these to ensure all are within tolerance. If you have to replace a sensor, be sure to have the tire dealer write down the new ID#. There is a dealer initialization process that they go thru, using a hand held TPMS tool.
The service manual for TPMS, indicates that there is a small black reset button to the left of the glove compartment (after opening it). I haven't personally done this, and proceed further on your own risk....all standard legal and self diagnosis disclaimers apply. It appears that the reset process is as follows. Inflate all the tires to their correct pressure. Turn on the Ignition, hold the reset button for greater than 3 secs. When the initialization begins it will blink the TPMS light 3 times, on and off for a second each. The TPMS ECM will then begin reading the sensors, taking approximately a minute per read. The initialization is completed, when the ECM reads successfully from all 5 sensors the pressure.
Note: it is not real clear to me whether this reset process can be used if a sensor was replaced, or whether this is just used to reset after a low tire pressure detection. There is a separate area of the TPMS service manual, which has a statement that the dealer intialization has to be used to 'register' the new TPMS ID.