Delayed DeadBall, batter Inf

[BSBAL18]

Couple questions i am throwing into one thread...High SChool baseball rules

Aa) Delayed dead ball situation. Is there a signal an ump should make to inform coaches/players/etc that a delayed dead ball is in effect?

Ab) R1 on first running towards 2nd on a line drive to left field, the 2B hinders his run and he has to slow down and alter his pace, so obstruction on 2B, but there is no play. End of play, R1 safely at 3rd. Since the obstruction happened on the first base side of 2nd, is this a no call? or does the obstruction get tacked on at the end of the play and R1 is awarded one base (home)?

Ba) Count 1-1, runner on first. Batter swings and hits catchers mitt on the followthru. This is batter interference, but the runner was not stealing (no play to interfere with), so this is a no-call, correct?

Bb) Count 1-1, no runner. Batter swings and hits catchers mitt during his swing (NOT the followthru) and this is catchers interference. is that automatic interference call and batter takes first base?

Really looking for catcher INt vs batter INT, and if there is no play out in the field to be had, then no batter interference to be called, but catchers int is automatic dead ball, batter gets awarded first base and any other runners return to base Time of Pitch, unless of course there is a runner on first who will be sent to 2nd since the batter is taking first base.