It's the day of graduation for Q, Radar, Ben, and Lacy, but after much cyber snooping Q finds an online comment telling where Margo is. The only problem is, she's in New York and is leaving the destination at 12pm the next day. The drive will take around 23 hours, so in order to get there in time they must skip graduation  and leave right away. Ben and Radar are still in their graduation gowns, with nothing underneath. After 22 hours of driving, getting in a crash, and peeing in beer bottles they get off the highway. Sometime later they see Margo's car, and soon find her in a barn writing! The book ends with Margo  continuing her adventure to N.Y.C., Q was supposed to come, but he has a life, a family at home. 

Q2 Does the main character change by the end of the book?

Yes, I do think Quentin has changed through out the book. Quentin started off as a very quiet boy who wouldn't like or do the things (adventures) that Margo does, but by the end of the book Q, likes the abandon minimart that MArgo has lead him to. 

Q5 Is the ending satisfying?

I don't think the ending of Paper Towns was that great. It ended with Q and Margo kissing then leavin Q, back to Orlando and Margo, to finish her adventure in New York City.  If i chose the ending I would have had Q= Margo finish their ending, together, like planed