
Hi,
As Anwen says, there are so many questions there you will need to
register to give us more details if we are to help you.
Basically, he will be friendly with kids if you raise him and train him properly, and the kids are well-behaved with him. I don't think Belgian Shepherds (which variety by the way?) are renowned for being good guard dogs, but I'm sure a breed specialist will be able to tell you more.
Are you in the UK? If so, and he is KC registered, his breeder is required to give you a diet sheet detailing his feeding requirements - stick with what he is used to for a couple of weeks till he is settled in with you. Is he used to living outside? If he has been house-reared, it would be unwise to move him outside straight away.
An excellent book to help you with training and playing with him is "The Perfect Puppy" by Gwen Bailey. All puppy owners find it very helpful.
Hope this helps.