I went to Penn.
I would highly recommend going to Penn - the student atmosphere is amazing, there is no shortage of stuff to do (whether it be going into the city, staying on campus, or going to a frat party at night) and the classes are also generally great, as long as you can get some good ones approved. If you stay in a college house there will be heaps of events that allow you to bond with other people at your college, and there are heaps of clubs and associations you can consider joining so the social aspect is great. Also, Penn tries to help the exchange students connect so you get to hang with a lot of people that aren't American which is kind of good at some points (eg if you want to go on a holiday somewhere, want to visit something overly touristy etc).
Living expenses - my college accom was 4000, you can pretty much find the amount you would be expected to pay for each place on the Penn website though. You can buy a food plan (2000) but at Penn, heaps of people have this and they often can get you in free off of it, like exchange students are usually more than happy to do it. Plus heaps of the good food is on campus but at chains rather than dining halls. I recommend not getting a food plan and going for paying your own way in which you can expect to spend around the same amnt on food. You need health insurance so that's another 1500 - you can't enrol without American health insurance but Penn offers a student plan for you.
My house was Gregory, which has been updated recently, and I was in a quad room. It wasn't my first choice, but I really liked it! It had a tight knit atmosphere, and I got to know heaps of people I lived with well even though they weren't necessarily roommates. I had three roommates and we each had sep rooms, which I really appreciated, but it depends what you're after. We had our own private bathroom, which was something that I really wanted. I would recommend either Gregory or a high rise (which were my first choice - but I didn't get allocated any of those and definitely don't have any reservations about ending up with Gregory in the end).
I didn't find it hard to get into my chosen Penn subjects at all - I got all the subjects I wanted to do. I even started this one subject, found it too similar to Human Phys, switched into something else under a Psych code and then switched into a biological code for it a little later on. Often there are multiple codes for the same subject (eg same subject offered by two faculties) so look into that because sometimes different faculties are allocated a diff number of places for students. I had no issues but did mostly Science subs so they tended to be large class sizes. Most of my friends got to study the classes they wanted to, too.
The GPA cutoff when I went was around 84 for CAS. I'm unsure if it has gone up or down since then. For Engineering it was around 79.