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His adult weight would be very difficult (impossible) to predict at 8 weeks. Just because the parents were that size doesn't mean their offspring will be. You might be able to take a look at grandparents and great grandparents to get a better idea. Seven pounds is very possible.
I will leave potty training to other members because I am just not good at it.
When he starts chewing, tell him no firmly and replace with an acceptable chew.