If you do send a thank you, it should be by regular mail.
You can include things about what you talked about, but it should be first and foremost in my opinion a thank you, so you should express thanks for what information they were able to give you about the school not thank them for listening to you talk about yourself.
I think it is a bit crass to highlight your qualifications.
As for interest, I’m not really sure…mainly because they know you’re interested otherwise you wouldn’t have interviewed there.
Unless they really are your number one choice far and away and you have concrete specific reasons for them being so far ahead.