Bottle Soap and Car Seat Newborn Insert

Hi all!  I have two questions.  We used to use dapple bottle soap to clean all of our bottles.  We ran out and just started using Palmolive because we figured soap is soap.  But I can smell the soap after they have been washed, rinsed and dried.  I washed them and my fiancé washed them a different day and it happened to us both.  Do I just go back to Dapple?  Does anyone else recommend a brand?
Also, I noticed my LO's head was at the top of her newborn insert and I looked up when to take it out.  Chicco says to take it out at 11 pounds but I see people with the same car seat and much bigger babies still using it.  I will be taking it out because that is what the manufacturer recommends but why do people leave it in?  Just because they don't know better?  Is there a danger to leaving it in?  (I genuinely don't know what could happen if left in)
Thanks guys!