OK, I'll bite.
Assuming you didn't badly bunger the head with the pliers, and assuming that you were able to reestablish normal cartridge overall length (you have others from the box, right?) you should be able to fire that round.
Here's why you might not want to do so: neck tension is now very likely to be poor. If you can very carefully single feed the round, negating any possiblity of having the bullet telescope again, you should be just fine.
For obvious reasons, I would not feed the round from the magazine.
If you badly bungered the head even gentle insertion in the chamber may force the bullet back into the case. Therefore, if you proceed you might want to chamber, then extract and examine to see if the bullet telescoped on chambering.
TM, you have received sound advice from everyone who has posted. I'd toss the round, too.
And you seem to have missed an excellent point raised by Stealthy: there is a problem with this ammo/mag/gun combination. You ought to care.
Oh, yeah, the questions: no, you didn't likely damage the powder granules. No, you'll not likely have a squib load due to loss of "seal". As for your third question..........well, ask your father.
Sam