No. PRC (pre-Ranger course) is a preparatory school (I can't remember how long, 2-3 weeks?) that almost every major Army post runs in order to get candidates prepared for Ranger school. PRC usually has its own PT entrance requirements, but I don't know what they are. I can tell you for sure, though, that he will finish out his deployment with his unit like normal, then, upon return, he'll go to PRC and Ranger school. My advice would be to take that post-deployment leave time period to get in good running shape. I sympathize--the five-mile run is what got me in Ranger school.
No he is not finishing his deployment with his unit. They selected 6 out of his Company, They are pulling them out of Afghanistan to attend Ranger School. I was surprised as well. If he can get past the Pre Ranger Course he leaves his unit 3 mos. ahead of everyone, he will finish Ranger School as his unit returns from deployment.
He did not drop a Ranger packet, he was planning on doing it after deployment, his Lt. was urging him to do it. They were selected by the Commander to attend.