1: No. I just did my interview on Sunday. I've been in Canada once in the past 5 years. They didn't ask about it.

2/3: I was able to schedule my interview as of March 23. I scheduled it for May 1. The system would have let me gone out further, but that was when I was at a border. Some locations have a long wait, so I do not think August would be a problem. Plus, there is the option to reschedule it.

4: You will not see Global Entry kiosks when coming from Canada. You will see NEXUS kiosks. But yes, you can use the Global Entry kiosks too.

BillJ