According to this reference, the pipe should be in the fitting 9/16" for 3/4 NPT threads.
This one states 0.400 inches for hand tight and 0.5457 for maximum. WRT the above 9/16 is 0.5625 inches, so some minor disagreement there.
This one agrees (within rounding error) with the second (0.400 and 0.546), and also provides a helpful guide for number of turns (4.5 to hand tight, 3 with wrench beyond that)
I also recall, but am not finding a reference for a rule of thumb that there should be 3 threads exposed past the fitting (the picture in the last link is particularly good at showing why, I think, but does not mention the RoT) This sprinkler document does provide something on that line, indicating a range of 3.4-3.9 threads for 1/4 to 1-1/4 pipe sizes, and up to 5.1 on some larger sizes.
And yes, despite any misleading information you may find on the internet, whether it's pipe dope or tape, it is a required "SEALANT" for the helical leak path at the thread roots. Lubrication is all well and good, but that not why it's used. I've personally moved from old-stye dope to teflon tape to new-style teflon dope. YMMV.