Apologies to the technically savvy members, but I need some help!

I'm attempting to rebuild the carb on my B&S Model 281707 Type 0411 12hp engine ... and have a couple questions ...


the rebuild kit includes a round green piece about 3/16" in diameter ... is that a "seat" for the float needle? And if so, do I simply push it to the bottom of the float needle hole? (When I disassembled the carb, I didn't see anything in the bottom of that hole ... although I suppose it could have deteriorated and fallen into the bowl.)
the nozzle that screws in from the bottom of the carb (located in the center of the float) doesn't want to unscrew with gentle force ... how likely am I to screw up the brass by putting additional force on the screwdriver? Would it help to heat the carb? How about some penetrating oil? I don't want to run the risk of making things worse ... so would I be better off to leave the old one in place, and just hose it down good with carb cleaner?


Thanks in advance for any help!