dome pistons but head work and cams would be recomended as-well

easiest way is to Deck the heads ( machine the surface of heads), thinner headgasket, dome pistons.

all cams like a certain compression to make them perform at there optimum, so the two options here are buy a cam that is suited to current compression or up the compression to a cam of choice

normally the higher the compression your are getting into a later intake closing or longer duration cam that carries its HP to the end and the earlier intake closeing smaller duration is for lower compressions but its a torque cam and comes on strong early but can give up quick and won't carry on with the HP

yep

Anything that alters the size of the combustion area, Raising the Compression is done by lessening combustion size, less area more bang. Altering the clearance between the cylinder head chamber and the top of the piston.

The most comman method is as Ando has put it.

To get a ratio for combustion, there is a simple math dymanic to measure it. Just google it.

It's more an exact science nowadays, to get the correct comp to work for the right purpose, just because you build something with big compression, doesn't equate straight to better HP.