Just bellow the rate box you will see "You will pay this rate at every payment cycle"
So, if you choose a payment cycle o 30 days with a rate of 1% it means you will be paying 1% per month of interest.
The methodology is better explained here: http://en.wikipedia.org/wiki/Fixed-rate_mortgage#Pricing
This is a great site that could really take off, but I think the ambiguity and cosmetic blemishes will scare investors away.
streblo,
We implemented the sorting for all relevant fields, the modification is online now.
As for the APR, we are working on that.
EDIT:
The payments calendar is online now too, to help people keep track of payments.
Fantastic: the calendar is really nice!!