What Are the Best Settings for Rendering and Importing Audio Data

I'm sure you guys and gals are much smarter than I am about this so I figured I'd reach out to you all!  I record at a sampling rate of 48 kHz at 24 bits. I'm unclear what the optimum settings should be on the Audio Data preferences. I have the Render Bit Depth set at 32 bits. Is 64 bits better? How about the Import Bit Depth, should that be set to Original or is higher better? 
 

I leave it set to Original, as, if the original bit depth is less than 24, bumping it up to 24 is not going to increase the dynamic range and, if the original bit depth is greater than 24, knocking it down will decrease it. 

I use the settings displayed in your screenshot for all 3. To my knowledge, there's no point in setting the record bit depth higher than 24 at this point, because there aren't audio interfaces that record at higher than 24. I like to do 32 for rendering, as, if I'm applying effects that add dynamic range (reverb tails come to mind) or if I'm combining tracks that have a cumulative dynamic range that is greater than 24 bits can represent, it will more accurately reproduce them.