And as for the pedals, the left hand pedal is a left hand thread. As others have said, pull the spanner up towards the back of the bike. They might be tight though, and a proper pedal spanner is worth having.
Once you get your new pedals on and go for a ride while clipped in, try and relax. I think a lot of issues people have when they're new to clipless pedals come from instinctively trying to lift their feet off the pedal while twisting, which makes it much harder to unclip. Try riding somewhere quiet without traffic for the first time and try unclipping and clipping back in while you're moving along, just to get used to it. You probably will fall over at some point, but you won't be the first, not by a long way!