I remember the rule of typed bonuses not stacking (there are exceptions) and bonuses from the same source not stacking. However other than the numerical bonus from the +1 not stacking I cannot find the rule for or against this.
You mention "General stacking rule" but I only remember it as I said above. If you can find and quote it or know the book its in that would help...my memory of it may just be fried lol
Also I cannot find where Flame burst says it does not stack with flaming.
In the case again is a ranged weapon with one shooting an arrow of the other.
Could you also point out where you found the bit about ranged weapons used as melee retain the enchantments? I know that in certain class abilities or feats it states that it works this way, but I didn't understand it to be general.
Again I just want to say I'm not arguing it, just trying to find where its at.