We've been looking to get a puppy or dog for a while now so decided to rehome one rather than just buy one. We recently rehomed 2 kittens who are just lovely and the children love them too. Seen a walked a lovely terrier cross today and taking the children up tomorrow to see her.
We're hoping to rehome her but they've said she is quite mouthy (expected this in a puppy) so it depends how they interact. My children are 2 and a half, 5 and 7 and are really good with the kittens.
I have done some reading but am quite a novice with dogs, dp has had dogs all his life so he knows quite a bit though.
The problem may not be so much your dc being good with the dog (and no small child should ever be left unsupervised with any dog) but with the 'mouthiness'. She is teething and it sounds like she has never been taught not to chew hands so you will need to be firm from day one and let her know it is not acceptable.
Terriers can be cracking little dogs and full of character, but they can also be very strong willed and need a firm but kind owner. If you get her, do enrol on training classes with her - if only to get her well socialised with other dogs, which can also be a problem area for terriers.
Get a good book and plenty of advice from the rescue centre. Dogs Trust have lots of good information to download on their website.