1) no, you should only need to prime it the first time
2) it goes in the glow plug hole (take the plug out first of course)
3) i tried it once and it caused it to run very lean for half a tank, so i dont know
4) too rich is just as bad as too lean. the engine needs to get up to proper running temps in order to work properly. get a temp guage and make sure you start tuning from the factory settings. look for a healthy trail of smoke out of the exhaust pipe and make sure it isnt bogging down or cutting out. if it bogs out at the hit of the throttle, your low speed needle (lsn) is a little rich so lean it an 1/8 turn at a time. if it cuts out at the hit of the throttle then its too lean, so richen the lsn by 1/8 turn at a time. if it bogs down at high speeds or is sluggish then the high speed needle is too rich, so lean it 1/8 turn at a time. if it cuts out at high speed the richen the hsn 1/8 turn at a time. when you think you are done tuning and it seems to run good them check the temp (it should be between 240-280F) just to make sure you didnt go overboard or to check for an engine problem