Injury/Correctable error?

[Bad Zebra]

Player A1 is fouled and injured driving to the basket. Coach is summoned to the floor to attend to injured A1. 2 free throws awarded. Player A1 recovers and officials mistakenly allow him (A1) to shoot a free throw. During dead ball following successful first attempt, official realizes error of letting player stay in the game. Official blows whistle, sends player out, explains errors to coaches, beckons sub to the free throw line to shoot.

Now...

1.) Is this a correctible error?
2.) What should be done with the first successful free throw point? leading to...
3.) How many shots awarded to sub?

[Edited by Bad Zebra on Dec 30th, 2005 at 09:20 AM]