Your Questions About Rough Collie Temperament

I need to find a dog that weighs 25-40 lbs I do a lot of hiking and has to be great with kids.?

Any ideas would be very helpful.

A Good Breeding with The Runt of the litter?

Every litter has a runt, but do you think even in a good breeding ( both parents health checked and cleared of passable genetic diseases and intelligent ) will the runt still be:
Slower
Tempermentally challenged
Have health problems
Be small

What is your definition of the runt?

Imo the runt could be the last born or the weaker sickly pup out of the litter.

Why not or why would you get the runt?

Golden and Rough Collie together?

I’m planning to buy a rough collie because I used to own 2 and they had the sweetest temperament i’ve ever seen in dogs! I currently have a 2.5 months hyper golden retriever at home. If I let them play together, will the golden’s hyperness rub off on the collie??