Is it that the brown ball worth 3 points and the green ball worth 4 points or is it vice versa?
Green 3, Brown 4.
If I pot my cue along with the red ball, do I get a -3 pts (red 1 pt and cue -4pts) or -4 pts (cue -4pts)?
4 points. You never gain any points on the same stroke as a foul. If you pot a coloured ball with a foul, it gets respotted, if you pot a red, it remains potted with no score given.
If my "on" ball is red and I hit say, a black. Is it -4 pts (misc offence -4 pts) or -7 pts (black worth 7 pts)?
4 unless the ball you hit has a score greater than 4, than the score of that ball.
If my "on" ball is say yellow (2 pts) and I hit say, a blue. Is it -4 pts (yellow 2 pts but min 4 pts) or -5 pts (blue worth 5 pts)?
The foul was on the blue. 5 points.
Is hitting a red to make that red pot another red counted as potting a red and worth 1 pt?
Yes, that's a cannon. Also, you can pot 2 reds with one stroke without it being a foul.
When all the reds are gone, everybody must hit the balls in order (yellow, green/brown, green/brown, blue, pink, black) without the option to choose which ball to hit?
Yes.
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Lovely.