Give it a go, perhaps.
Just don't stress about it. It is just another trip, say, you are travelling somewhere new! Go, do the interview, be yourself - if you don't like the school, too bad for them. Think about it this way: you have absolutely nothing to lose, right? You are in a position of power here. Give it a go, I say!
It is your choice and only you know your priorities so I don't think we can advise much.
But if you do need an opinion, then from what you told us MIIS sounds wonderful: more academic, in a prettier setting, and with a (much) greater concentration of native-speakers (if you are saying your goal is to reach impeccable English, than assuming that since you are currently in Shanghai you are Chinese, it would make sense to stay away from the 90%-Chinese student body of the UPenn programme).
Then again, you know more about the programmes, your career goals and prospects after these degrees. I wish you the very best with this decision!
Most importantly, congratulations! You have two offers!
As many as you feel comfortable with.
Some people go with one or two because they know exactly where they want to be and feel comfortable about their applications (or are short of cash). Some people go with 15+ because they feel safer that way.
Personally, I'd say that 8 is a good number. Have you contacted all those academics? Perhaps send them an e-mail, also read more about the funding and department resources on the university websites, and you will eventually cut 8 to a lesser number. But as I said, 8 will be fine with many.
I was wondering this.
I really hope no one checks.
I have a double spelling of my name. Not much comes up under my 'official' name (under which I applied), which can be both a good thing and a bad thing. Under the other spelling, the whole spectrum shows up: from academic prizes and student societies to my comments on random travel blogs.
I don't think anyone will care so no worries there. They might look at the course name (not guaranteed) but why would they need to verify the course ID?
I have heard that some students combined their best scores. So it is an established practice BUT probably not the most common practice, I am afraid. To be on the safe side, I'd say put the recent scores. Sorry if it's not the answer you were looking for.