So my 2 cents is:

RAF is only for 1-60, and it goes pretty fast. I personally would roll 4 new toons and quest/instance them up to 60 and then boost from 60-80.

I would also make sure I linked my accounts in a chain like you describe in your first post:

"Do I first link my current account (A) to one of the new ones (B), then (B) to the next new one (C) and then finally C to D?"

Yes, I would do this.

"Then I can use my current level 70 to help level the new guys and they in return level a new toon with the gifting levels?"

I would not use my current level 70, until after RAF had finished, I would level up 4 new toons to 60.

Then I could grant levels from D to a new character on C, C to a new character on B, B to a new character on A. You could RAF these new characters up to level 30 and then give them granted levels up to 60 from your just recently hit 60 toons.