Action Required....or Not

I feel like I don't know how to end conversations. Or perhaps I'm never sure when a conversation is actually over. Whenever having a conversation over the phone, I always wait until the other person hangs up. The ends of my online chats go something like this:

Mikey: Okay, well...I gotta go eat lunch.
Scooter: Okay, man, eat well.
Mikey: Okay, later.
Scooter: Later.
Mikey: Bye.
Scooter: You're still here?
Mikey: Uh, yeah.
Scooter: Leave, already.
Mikey: Okay.
Scooter: Well?
Mikey: I'm going, I'm going - my computer takes a while to shut down.
Scooter: Sigh. SIGH.
Mikey: Okay, this is for real. Later.
Scooter: GO. AWAY.

This has real world implications now, as I've received several emails from residency programs, some with ambiguous language as to whether they're expecting a reply from me. For example:

I am pleased to confirm and/or reconfirm your interview appointment, scheduled for Monday, Dec. 4, 2006 with the Internal Medicine Categorical Residency Program at the University of ....

Some programs are more concrete and clear, as in the following:

This is a reminder that you are scheduled to interview for a position in the Internal Medicine Residency Program at General Hospital on Friday, December 8, 2006. Please confirm by email that you will/or will not be attending this interview.

See? I like this. Clear directive. No questions as to whether they expect to hear from me or not. The other ones? I'm not so sure. And of course my mind is playing with my head, hinting that these confirmation letters are a test.

Like, what if I answer the ambiguous email but they're not expecting to hear from me? It could look too desperate:

Administrative Assistant: Lookey here. This applicant responded to the confirmation email confirming the confirmation.
Program Director: Why, how redundant. And a waste of internet bandwidth.
AA: And there's drool on the email.
PD: How can you drool on an email? Regardless, he's obviously too desperate to come here. Cancel his hotel reservation, disinvite him from the pre-interview dinner, find out if he has a dog - if so, kick it. And remove him from our rank list.

Or it could be the other way around. Clear communication, after all, is key in medicine:

AA: Mr. Program Director, it's been twenty-seven minutes since I sent the email, and Mikey has still not confirmed that he's coming to the interview.
PD: He's obviously not interested in us. His loss. Cancel his hotel reservation, disinvite him from the pre-interview dinner, leave a brown bag of flaming poo on his doorstep. And remove him from our rank list.

What to do?