Are dog "booties" necessary on rough trails? Opinions? Experience wih dogs on long, rough trails.

My husband and I do a lot of hiking. We just got our first dog, an Akita, who has proven to be hardworking, loyal, intelligent and a great outdoor enthusiast. As we take her on longer and tougher trails, I'm wondering if the rough scree and abrasive rock on the trails are hurting her paws. I know you can purchase "booties" for dogs to protect their feet, but are they necessary? I didn't think so until I felt how sharp scree fields can be when you don't have thick soled boots on! I'd appreciate any shared experience on this topic. Anyone had problems with their dogs feet being hurt on a rough, rocky trails? Do dog's foot pads naturally toughen up?

Also, we've introduced a light backpack and have been slowly adding weight to it.
Anyone have advise on how much weight can an adolensent working breed dog comfortably carry?

I'd appreciate any advise on hiking with my dog. "Ursa" is 10 months old, strong and active. She's already very well mannered on the trail. She's my first dog, though, and I want to make sure I'm not hurting her in my ignorance.