#1: yes, especially where I live. It varies with each body of water but as a top predator they bioaccumulate the most PCBs and mercury.
#2: yes this true with most if not all fish contaminants. Once again, this stuff accumulates and is always at highest concentrations in top predators
#3: yes it varies, like @J Franchosaid, check your local water quality. Where is it that you fish?
also I should ask how old are you? Older humans build up the contaminants just like the fish. At age 25 you might want to limit yourself to one or two a month. If you’re 75 go hog wild.