Making a play on a runner who reaches and passes first base...

[LMan]

I'll take a cut at this one:

a BR is out if, after reaching 1B, fails to "return at once to 1B after overrunning or oversliding that base" and is tagged (if going to 2B) or base is tagged (BR goes toward dugout or position). This could be after a walk or a single. Ball is live in either case.

The "has to turn to the foul line-side" is a baseball myth, IIRC. Nothing says he cant turn to the fair side, as long as he proceeds back to 1B.

I think most umps judge this as, only if the BR makes a clear attempt to abandon 1B and advance to 2B and is tagged, will it be called. But I could be wrong.