BHO questions

Few questions-

I'm using 1/8 of good quality bud, so how much butane should I use? Most guides I've seen suggest anywhere from 8oz-16oz of butane. I'm assuming for an 1/8 that 1-3oz would be more than enough

After placing bud into turkey baster, adding filter, and then adding butane, should I just let the butane drip out or should I squeeze it all out after a few minutes? I don't want to wait too long because I've read that the butane could pick up some of the plant matter that I don't want along with the THC.

How do I know if I've used too much butane? Is there a certain point at which a color change in the dripping butane would indicate that I'm only harming the purity of the oil?

Is there anything I could do with the left over bud? Assuming I left it out to dry, wouldn't it still have a decent cannabinoid profile so I could make cannabutter or something with it?

While the butane solution is sitting in it's evaporating dish could I use a small paint brush to apply some of the butane solution onto rolling papers and let the butane evaporate off the rolling papers, giving me hash infused papers?


Thanks