Some people report horror stories when going to clipless. To me, SPDs are so easy to get out of, that I don't even think about it. Definitely try them out on grass the first time (and unclip while you still have plenty of momentum. You don't want to be almost at a stop and have to track stand while you get your foot out).

I'd go with the double sided version. If you want to still ride in normal shoes, they make double sided clipless that still have a cage around them.