I won't get into the carseat part much b/c tmcp2001 has said it well. My 3 year old son is still rearfacing and will be until he hits 35lbs (limit of the seat) then will be in a harness till 80 lbs. Carseat safety is something I don't play around with! When it comes to rearfacing, my motto is "broken legs-cast it. broken neck- casket." Meaning, don't worry about the legs, worry about the neck. If the crash is enough to break legs, it would have broken a neck.
Teething necklaces....awesome!! My daughter wears one and I never know a tooth is coming through until I see it. I also wear a bracelet for pain I have from an injury. It's amazing!! Here's where we got ours:
http://hyenacart.com/inspiredbyfinn/