You should be able to tell the dog's basic personality when you meet him/her, there's no way to tell personality from the breed mix. Same for weight (anywhere between a Sheltie and a Golden), though a 7-month-old won't get much larger, but will just fill out a bit. A dog who is is 25 pounds at 7 months will probably top out at 35 pounds or so. Whether a dog is good with kids and other animals or not depends on the individual dog.