I would be doing some flea checks on him, dab them with a Qtip dipped in rubbing alchohol , fleas on a puppy this young is not good , they are bloodsuckers
Do you have other animals? cats that go outside and come in? You may have to treat your house to stop the reproduction.
If your backyard is a clean environment there is absolutely no reason you cannot take him outside to potty...You don't want him to get in the habit of pottying in the house, on papers, pee pads or you'll have a harder time housebreaking him.
He's very cute