I'll give it a shot for a dumb down version.

The more radical your engine the more initial timing can benefit your idle RPM and crispness. If you go too far advanced you will have trouble with starter kickback and slow hot starts. There are several strategies to deal with this in a street car the simplest is don't set it too high. After you figure out what initial (idle) timing you want to run you can set the total for a reasonable number and possibly fine tune it at the track. Stock distributors are set to a wider spread so they need to have slots shortened inside. Different aftermarket units use different methods.

Once your timing is good you can tune the carb. Hopefully it's in the ballpark so you can get the timing! On a holley style carb the circuits 'stack' up. As you open the carb more fuel flows out of different spots.

At idle the fuel emulsion (pre mixed with some air) comes from a small hole below the butterfly and also from the bottom of the transfer slot exposed below the blade. You want to keep the t-slot exposed under there small, looking like a square. Then tune for highest vacuum with the idle corner screws.

As the throttle opens the transition slot begins to flow, and then the mains. If it is opened fast enough you will shoot the accelerator pump to cover a lean spot as the fuel begins to flow. Drop the vacuum enough and the power valve will flow too.

A holley is pretty easy to tune for racing. For street driving the more time you spend driving like a normal person the more the carb is unnecessarily rich. If you drive like them Duke boys you'll be fine. Thats why some people want you to follow them to a race- they know boppin around will foul out your plugs and your rig will run like poop...