Ok, Bella is best at this sort of stuff but here is my tupennceworth!
Biting, ankles, hands or anywhere; a stern no and then offer a toy he can chew on straight away saying "here you go" or whatever in an up voice. The idea being to show him biting people gets a bad response but biting toys gets a good one.
Spend plenty of time playing with toys with him during the day, even a couple of minutes is better than nothing. Start teaching him very basic commands, sit, down and so on. Do few minutes at a time regularly, it will keep his mind occupied as well as stopping him trying to get your attention by nipping.
Excercise, little and often, even just gettinghim to trot round the garden with you with lots of encouraging words and so on will focus his mind on you without the nipping.
Tell the children to be calm around him, when they run and shout he does the same, but hi version is jump and nip - because that is what puppies do. Tell them to walk, stand still, talk calmly when he is in the room. If he runs up to them they are to stand still and wait to see what he is doing, if he sniffs them they can walk off, give him a pat on his back and carry on, if he opens his mouth they have to give the firm no (deep calm voice) you should always be there to back that up if needs be.
Get a crate, or even a cardboard box that is his place only, this is his spot to be calm, the dc don't go there and no games are played. Encourage him to go there with his chews or bones to reinforce that this is a relaxing space.
Hoepfully Bella will give you some more ideas but those are my thoughts to start off with!