Hi Abe,
Well as far as the astronauts using the ham gear, it would have to be used on their 'free time' when they are not doing assigned work. But like the interview you heard, that was something scheduled so you would not be able to talk to them on a one to one basis unless you were part of the interviewing crew or classroom.
When they do get on there during their free time, it is madness for them. Just think of yourself being the one in space and everyone wanting a contact. You reception footprint on the earth is a few thousand square miles and all you get in intermod from hundreds of Hams transmitting FM carriers trying to talk to you. After a bit, you don't want to even do that anymore, so if a ham gets a contact he is lucky.
I am one of the lucky ones who have had a contact with an astronaut, but that was on the space shuttle. I have never had an ISS contact, but basically if you do get a contact, all he will do is acknowledge your callsign and go on. There will be no conversation take place between you and him or her because of that same intermod, even though you hear no one else, he/she is covered up with callsign after callsign being tossed at them.
I hope this answered your question, take care neighbor.