If I get a W-2C, do i just fill in the info that is included in my W-2C? or do I fill in the info that was in my W-2 but correct the discrepancies listed in my W-2C?

Your form W2 entry will be a combination of the original W2 and the corrected W2C.  You will make one W2 entry in TurboTax.  The W2 information you enter will include all the original form W2 information that did not change plus the corrected items/boxes from the W2c.