Check out the BR FAQ. It's in the Misc section, probably somewhere in the first few pages. Covers a lot of that stuff in detail.
The pin is a small dot, about 3/8", that marks the top of the weight block.
The PAP is the positive axis point, the point on the surface that marks the initial axis your roll the ball on. If your PAP was at the north pole, it would spin like a top.
The HMB is Hammer's way of marking the mass bias, PSA, or whatever you want to call it for a ball with an asymmetric core. Brunswick uses a small white dot (like the pin, but about 1/4"), as do most of the companies that Brunswick manufactures. Storm puts "RAD" or something like that (related to the name of the core). Track puts a little picture or "RC". Ebonite puts a bomb symbol.
Distances like 5" pin-to-PAP mean that the pin is 5" from the PAP. Higher numbers usually mean later reactions, shorter usually means earlier. Pin above or below is usually above or below the fingers. Above is later, below is earlier. Degrees is the angle between the pin-PAP line and the pin-CG or pin-MB line. Pin length is the distance between the pin and CG, top weight is how much heavier the top is than the bottom if you put the CG at the north pole and slice the ball in half along the equator.
SH