The Pro-Mod guitars have a 'coil split' function: is this the same as a coil-tap?

Yes and no. What most people think of as being a coil tap is actually a coil split. A coil split, like on these Charvels, is when the circuit shuts off one of the coils of the humbucker so that what you hear is a single coil sound. A coil tap is when the circuit halves the power of the pickup so it is essentially a half-powered humbucker. The effect is similar but not the same as an actual coil split.

What is the difference between the Pro-Mod San Dimas and So Cal guitars?

The San Dimas and So-Cal names refer to a spec rather than a model, so you'll find San Dimas guitars that have S-style bodies and T-style bodies. The only real differences between the two are that the So-Cal has a pickguard and the San Dimas does not, and the choice of pickups: the So-Cal has Seymour Duncan Distortion pickups whilst the San Dimas has a JB and a '59.

Where are the Charvel Pro-Mod guitars made?

They are made in Mexico to superbly high quality levels.

I've heard something about these guitars having a 'no-load' tone control: what is that?

It's a simple idea but a very effective one: turning the tone knob from 1 through to 9 gives you the expected low-pass filter type of standard tone manipulation. Turning it to ten actually removes the tone circuit from your signal path, letting it go straight to the output jack. This means you are getting more of the signal coming out, resulting in a hotter output. Lovely!

The Charvel Pro Mod guitars have a compound radius fingerboard. What does 'compound radius' mean?

Compound radius refers to the curve of the fingerboard. 12" is already pretty flat, which is good news for shredders! A compound radius like the 12-16" ones on these Charvel guitars mean that the fingerboard begins flat and gets even flatter as it goes up towards the upper frets. This is a great thing for any technical player.