Off lead: yes, definitely, though getting one to come back when he has spotted a squirrel can be a problem sometimes.
Generally fine with other dogs, though my male border sometimes takes against younger, bigger, un-neutered males - he feels threatened, so gets in first with a growl. He has never caused an actual fight but will snarl at them to go away.
Not good with cats, but that may be different if they grow up with cats in the house.
Excellent with children - ignores toddlers, plays nicely with older kids, very patient and tolerant (obviously a lot of this is socialisation, exposure and training when young).
Barking: generally only at cats/foxes/squirrels, or briefly if he gets excited when someone comes home. Doesn't do random yapping.
Clingy - hard to say. He is very attached to me, as his main person, and has got clingier during Covid because I have been around more, but I can still go out and leave him for four hours or so, occasionally a little longer if necessary.
I would definitely recommend borders as a relatively low-maintenance, fun to have around kind of dog. The puppy stage is quite hard work, but that's true of all dogs.