Weird experience with BU Chemistry application

[ulyssesithaka]

I've had an unusual experience regarding my application to Boston University for their chemistry PhD program. I did not receive any information about the status of my application till mid February, when a PI of my interest contacted me asking for a Skype interview. They never followed up on my reply though, even after a reminder, and so I never had that Skype interview. Then at the end of February I got an email from the grad office saying I was on a small waitlist, stating that they could only make a limited number of initial offers and that they didn't have space for me in that initial round, hence the waitlist. I responded to that waitlist email basically saying thank you and that I look forward to the result.

So my questions:

1) Is it worrying that the PI never had the Skype call?

2) Is the waitlist email a standard boilerplate response?

3) What would my chances be of getting through the waitlist? BU is very high up on my priority list of universities.

4) Is there anything else I should do, or just wait till the 15 April deadline and see what happens?

Btw, I'm an international student, if that would be of any relevance.