Yes. Signs of overfeeding include spitting up excessively after a feeding, numerous large stools, and rapid weight gain. Cues that frequently are ignored are a disinterest in feeding and turning the head.
Yes. Yes - and this is quite common now. Babies are often overfed because parents confuse the need to calm with the need to eat. Babies use sucking as a calming mechanism (hence older kids sucking their thumbs, etc) and may just want to fall asleep or calm down. If you are constantly feeding or baby drinks more than 24-32 ounces per day, then you are overfeeding.