How do I know what projections to use.

Put your pin near your job on the map, then you have 2 options Meters or Feet with suggestions.

If you put a pin on your data in the map view near your collection point it will give you the proper suggestions for both your CRS and your Re-Projection. You can select Meters or Feet and then you select your desired output projection from the suggestions that it gives you. 

This works for all CRS and Reprojections both Horizontal and Vertical. 

CRS (1)

CRS Suggestions