hm..

1-the flame can be anywhere just under the weed thats all...swirl though..dont hold in one spot..
2-well what i do is warm it for about 10sec. then after another 10 i take a long deep suck and i can feel the vap..and only see a VERY slight smoke in the right light..otherwise u cant see it..let it cool of from time to time..
3-the weed isnt good when it starts to taste different..you'll know when that taste kicks in..plus the buds are all black n burnt
4-i dont know...lol