Explosives were found "rigged on remote control cars" (in San Bernardino)

[Straw Man]

37. That's not a point.

It's a question -- actually, a series of questions.

What's the penalty for making a straw purchase (that is, one where the buyer who is eligible to purchase and own a firearm does so just to hand it over to a person who is not eligible to own that firearm)? Is it a small fine? A big fine? Is jail time involved?

It's a felony, punishable by up to 10 years in prison and fines of up to $250,000.

http://smartgunlaws.org/straw-purchases-policy-summary/

As far as actual prosecution and sentencing, I would imagine that it varies. In a high-profile case a few years ago in New York, the straw buyer got eight years.

https://en.wikipedia.org/wiki/2012_Webster,_New_York_shooting

Is the straw buyer on the hook for any crimes committed by the ineligible end user?

No, unless it can be proven that they were part of a conspiracy to commit these crimes.

Is there a database to track what happens to a gun after it passes out of the original buyer's hands?

It varies from state to state. In California, there is.

Although I have a sneaking suspicion I know the answers (and why things are the way they are), I'm happy to cure my ignorance and be 100% wrong.

Does that conform to your "sneaking suspicion"?