1. Already answered.
2. I agree that LTSpice is the best free simulation tool.
3. I'm a GEDA user, but KiCAD is getting alot of chatter these days.
4. The GEDA suite is the only open source suite that I'm aware of to do all of this. There are commercial packages that do it as well. That said, even though I use GEDA for capture and layout, I use LTSpice for simulation.