Another thing about feedback - some programs do thrive on hearing from applicants. A couple of places I visited, they told me that if I was interested in their program, I would be advised to let them know that. One PD said he would be more likely to rank people higher if he knew they had a strong interest in his program, specifically. He wasn't asking for #1 ranking, but I think wanted a sense of level of committment, or whether I was just visiting for some other reason. I told him that I would not visit any program I wasn't seriously considering, but I would let him know where they stand. Another one said, "We only rank candidates who are seriously interested in our program, so let us know." So feedback goes both ways. I have heard from other places though that they rank applicants without trying to ascertain this. Of course, if probably doesn't hurt your chances to tell them that you really like their program. but don't lie if you are going to rank it #10 and say it is one of your top choices.
Second looks, more for your information I think. Programs are busy. Again, probably won't hurt your chances. But I don't think it hurts you if you don't do it, either.
I have gotten more feedback in the last couple of weeks, including a hand written note from one department chairman which was quite nice.
The most specific things I have heard are "you will be highly ranked," and "you are a very strong candidate, we would love for you to come to our program." I guess what those mean depend on semantics.