Oh, essays could be written if you want to cover everything...
Quickly covering the ones you've mentioned, negative camber allows more tyre contact patch to the ground as the car rolls, so you'll get more lateral grip. It's all dependent on how much you car rolls though, so you can end up taking grip away when you want to add it.
More holes in pistons/larger size holes softens the shock up slightly, as it's easier for the piston to pass through the body of oil. Changes how much "pack" your car has on jumps and on landings, so generally if the car feels like it's getting kicked around by bumps or ruts, go up in pistons. If your car feels a bit lethargic on a smooth track, go down in pistons - it'll sharpen the car up a bit and you'll notice it jumping further. It's all about how the suspension as a whole soaks up bumps.
Shock positions, the further in you move the shock on the tower, the softer it'll feel on initial compression - it'll roll a bit more and you'll get more grip. Standing up the shock more makes the compression linear. In terms of arm positions, further in makes the shock feel softer, and it'll soak up bumps a little better. The further out you go on the arm the more stable it'll feel.
Weight placements, if you need more steering at the expense of responsiveness or you need to keep the nose down, add weight to the front. If you need more traction, add weight to the rear, or if you're running a shorty transverse in the rear position add a LiPo weight. It's just about getting a balance you feel comfortable with.