T/Th have been the MD interview days and W is when the MD/PhD committee and grad programs interview candidates (so that they can go to either the T/Th MD interview).
There is a student hosting program which you probably weren't told about because they just started recruiting this year's students in past couple of weeks (since school just started). Just email the admissions committee for the hosting program's website which has student contact info. If you're interviewing MD/PhD, just let the MD/PhD admissions person know that you'd like a host and we find one of the current MD/PhD program students to host you.
I know it's a hassle to get here because I was going to school in California when I interviewed and then had to come here for a two day interview. Still, I think it's worth it.
About the loans: My brother is a first year med student at USC and he told me that the subsidized federal loans are going away for graduate students. That being said, subsidized loans are only available on the first ~$8,500 per year. I believe that the old total max of sub+unsub of ~$38,000 will still exist, it will just be all unsub.
Soapbox time:
Med school is expensive and many students underestimate the burden of having a lot of loans. I shouldn't really have a voice on this issue since I'm MD/PhD, but I told my brother that he should go to the cheapest U.S. allopathic school he got into; he ignored my advice. I am very happy, however, that my (now) wife followed that advice when she chose a med school. She went to a med school that she didn't particularly like but now she can afford to do general pediatrics and can even hope to make a dent in her loans as a resident. As much as I love Dartmouth, I honestly don't think any one U.S. allopathic school is worth $100k+ more in loans than any other.