Aussie Owners help me out ..I need advice

So we have been thinking of adding another dog to the mix and I was looking at maybe an Australian Shepard (Aussie) ....I guess I should tell you a bit about us.We live in a single family home about an acre yard totally fenced in (6ft in back 4ft around the front part)we currently have Boston Terriers 3 females and 4 children living in the home ages 3,5,9 and 11 years old all boys.I am a stay at home mom so working and time away from home is not a problem.My 11yr old has expressed and interest in having his own dog something all his (as in not a BT) a dog he can teach new tricks and maybe go into advanced obedience,rally or agility with.(We would be doing basic obedience anyway)

So my questions are

How active are Aussie's in general are they bouncing off the walls all day long ? How much exercise do yours require ?

How are they with other smaller breeds (and young puppies),How are they with other animals in general ?

How are they with children (remember my youngest are 3 and 5) ? Can they take alot of noise and running around ect ? Are they gentle with young ones ?

Are they escape artist's do they in general like to dig and get out and run ?

Do you see any differences male vs female ?

I see alot of breeders breeding mini and other types of Aussie what size range should a well bred Aussie range? and what health testing should I be looking for any breeder referrals would be great!!!