Baseball question: Fair or Foul? Interference, Obstruction, or no call?

In a baseball game using professional style rules: R1 on first base, no outs. Batter hits a high infield flyball toward 1st base. R1 returns back to the base and stands directly on it. First baseman (1B) moves into position for the catch but accidentally bumps into R1 while he's on the base. 1B stumbles and... show more In a baseball game using professional style rules:
R1 on first base, no outs.

Batter hits a high infield flyball toward 1st base. R1 returns back to the base and stands directly on it.

First baseman (1B) moves into position for the catch but accidentally bumps into R1 while he's on the base. 1B stumbles and falls down as a result of accidental contact.

The ball falls to the ground. Initially it hits about 1 foot foul and 2 feet in front of first base. The ball lands on a small rock causing it to take a weird bounce toward the infield where it strikes R1 in the foot which is directly on top of the base.

1B picks up the ball, tags R1 (while he's still on the base,) then tags 1st base.

Clarifying info: The batter-runner is still at home plate because he thinks its a foul ball. The collision was not intentional or malicious by either player, and it occurred while R1 was touching 1st base.

The offense's head coach wants you to call it incidental contact (no call) and declare it a foul ball.

The defensive coach wants you to call it a fair ball and a double play.

R1 says he was obstructed and thinks he should get a free base

1B says he was interfered with and wants the runner called out.

Whats the call and how do you explain it to the coach who wants a detailed explanation?

Is the ball fair or foul?

Is there obstruction, interference or no call?

Which runners are safe or out and what base do they get?
Update: Update, the ball lands foul in front of the base, bounces to touch R1's foot on top of 1st base, then rolls beyond the base into foul territory where it is picked up by 1B.
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