I have some questions about aftercare for bark grafts made on large limbs. But first, thanks to all who have put forth the great on this forum that gave me the courage to cut a number of main limbs off my mature apple trees.

I bark grafted to limb stubs between 3 and 5 inches in diameter, using several scions per stub, every 2 inches or so along the circumference.

Here's a photo of one tree. It was a variety I don't like, and structure was poor with branching starting very high up. I cut back some of main limbs to graft and become the new scaffolds for the tree. I left some of the limbs in place for now to avoid overly shocking the tree, and pruned drastically to let light down to the graft zones:

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Here's one graft site a couple weeks after grafting in April just starting to bud out:

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Here's the same grafts now, ready to prune(?):

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I have some questions about the proper aftercare of this type of graft:

2. On the smaller limbs, I plan to cut back soon to one scion. How close to the cut surface of the limb stub should I cut the redundant scions? Is my understanding that the extra stubs help the callusing process correct? Any idea how or why this works?

3. On the larger limbs, would it be OK to leave two scions to form permanent scaffolds? Would they eventually fuse together properly, or would they form a weak attachment when they grow together?

4. I'm wondering what the best way to train the shoots from the remaining scion. I'm interested in inducing low branching, and not just have shoots shooting for the sky. I thought maybe I could pinch them at 2 or three feet to induce brancing, and use weights to pull all shoots down to good angle. Or what other/better plan have the experts used to build a good branch structure?

5. Is there a danger of letting the scion shoots get too big the first season, causing the scion to break off?
   

Thanks - appreciate any insights!