IR or nothing?

[FMadera]

1. No, you don't have to blow the whistle. Wave it off, play the rally, and administer the IR at the first dead ball.

2. No, once you blow the whistle, it's a team delay warning. No sub allowed.

Since you have a team delay warning, you can fix what would have been an illegal libero replacement. So you should have allowed that, since you've already got a delay assessed. Let them complete the replacement, delay warning, play on with the home team still serving.