The schematic for the Bar30 board has C1 and C2 as 1uF decoupling capacitors, which is in line with the reference design for the voltage regulator. If you don’t need the voltage regulator (in the case where you plan to supply 3.3V rather than 5V) you can drop that part of the circuit and one of the capacitors. The reference design from TE indicates you should have at least a 100pF decoupling cap for the MS5837-30BA, so the 1uF is fine. I’d also add 10k pull-up resistors to SDA and SCL as well.
As for ratings and individual part selection, that’s pretty dependent on the rest of your design. The Bar30 calls for 0402 package caps, so probably rated for 10V. The actual diode is a SOD-523 package but the value isn’t specified in the schematic. You probably will want a Schottky diode rated for you particular application. Something like these - https://www.vishay.com/diodes/ss-schottky/sod523-package/.