1. Shimano SPD is a good system to start with. I'm currently using Scott Tour shoes and Nashbar Ragster sandals.
2. Yes and yes. Been using various clipless systems in the last 10 years(SPD, Look, Eggbeaters, Speedplay, MKS, etc.).
I've slid on a wet plate in the rain and black ice; haven't tumbled yet because I couldn't clip out in time: