1) Lack of attention to dad when he is interested in a bug, dog, cat, smell etc....
Normal.
That tells me you're in an area with too many distractions for him, and you perhaps need to move back indoors, and work on "watch me" before you progess to an area with more scents, sights, and sounds.
Rule of thumb is "No eyes, no ears", aka, if your pup isn't looking at you, he's not paying attention to you.
2) Overwhelmed by big dogs and rough play.
Big dogs need to learn to play nicely with little ones. See if you can find a "Veteran" of playing with small dogs, and introduce Kota to them, so he can learn that big dogs aren't all evil jerks who are going to try and squash him.
3) Not very food motivated
Motivation for food is talking more about during a training scenario than during meal time. My GSD is extremely food driven, but he's not a fast eater. Eager to eat? Sure, but...it's not quite the same.
Don't leave the food down so long. 15-20 minutes, and then it's up, up, and away! Tough noogies until next meal.
4) He still pulls at my pants and shoelaces
I'd expect that for awhile yet. If ignoring isn't working,
gently disengage him from your pants, say "No chew!" and make sure you have something to trade with him (a stuffie toy, chew bone, etc), and praise him for chewing that.
If he persists, place him in his kennel with a kong for a few minutes. A little "time out". He doesn't associate the kennel with anything bad this way, AND you can get a puppy break and attempt to save your clothing.
Friends come in all sizes, shapes, colors and races.
They can do it, why can't we?

Marcato Shepherds
Where it's about function, not flash