If you have any questions at all about carb function then you definitely want to only do 1 thing at a time, that way you know what has caused what.
Before initiating jetting/tuning you must be sure the exhaust system has no air leaks, otherwise you cannot be sure if any backfiring is from the exhaust or carb problems.
Work on one  carb circuit at a time.  Do the low range (pilot), then midrange (needle),  then the high range(main jet).
Be sure you understand what you are doing and why, it will help you avoid a LOT OF FRUSTRATION and save a lot of time redoning the jetting over and over again.