1. I think most younger years got on his side once or twice, but funny enough, enough though Percy was hard on them, he always went out of his way to make sure he didn't have to report them to McGonagall - better they get on Percy's bad side than hers *snickers*. But yeah, definitely friendlyish now. Percy's a good customer, often steps in when there's disagreements, and worse come worse, can transfigure any offenders into the creature of his choice (and yes, turning you into a sea urchin is his way of calling you a prick).
2. Sounds good! Plus Percy has a healthy respect for Ravenclaws of all sorts.
3. That just means she has the wonderful opportunity of meeting him for the very first time without preconceived notions ;)