Not really dabbled in such high pressure measurement before, mainly low pressure changes like altimeters or varios. Looks like the link Pakitos sent you is very useful. Looks like there are various devices available. The one I spotted is up to 350bar and gives a frequency output that is proportional to pressure, you could use a micros counter/timer to measure the frequency and then drive a display. Looks like I2C etc is a possibility also. As to temperature, if it is outside the cylinder, you could any number of devices. If it need to be inside, I guess it would need to be something more specialized. As I said, a little bit out of my field. Good luck anyway.