The number of vents depends on how and where the various fixtures are located, and has nothing to do with how far they are from the pipe or where the toilet is located.1.Can I get away with using only two vents to vent everything? The total run from the sink to ejector pit will be about 6 feet, with the toilet in the middle?
You can put it anywhere you want to as long as the drain and vents are proper.2. Can the toilet drain be in the middle like I have it?
THAT depends on your building department. Various codes and locatlities have different requirements. It should be indicated on your approved drawing and permit, what sizes and where the vents are required.If I can get away with two vents, can they be 1 1/2" or must they be 2"?