The key words are Swift and Next Attack
Swift Actions
In D&D3.5e, you may only perform one swift action per turn, even if it is a mental action. So, you would only be able to activate Dislocator once per turn, at the most.
Next Attack
Multishot and similar abilities and effects produce additional projectiles as additional attacks. When you're firing two arrows, you're really making two attacks. So the one you designate as the "first" attack will be the "next" attack for Dislocator. Even if you could activate it more than once per turn, you'd have to activate it before each attack, meaning it would have to be in-between the arrows produced by Multishot, which isn't possible.
I really liked this question because of the idea of the idea of hitting someone with so many arrows that they poof and appear in the air, but unfortunately, it's not possible with that set up. Alternatively, you could hire four wizards of sufficiently high enough level to simulate the effect in battle.
"Look at what my arrows did!"
The four wizards are high-fiving each other in the background while looking mentally exhausted.
Edit: One thing I neglected to mention is that Dislocator mentions your next "successful" attack. Meaning that if your first three arrows miss and your fourth arrow hits, they would have to make a Will save. Still, you cannot force your opponent to make more than one Will save per turn in this way.
Probably Not
The status of gauntlets, cesti, rope gauntlets, and other weapons of that sort has never been officially FAQed, but Sean Reynolds and James Jacobs have made forum statements that no, these all count as weapons and therefore are not vectors for enchanting unarmed strikes (nor do they count as unarmed strikes for monk or brawler improved unarmed damage, stunning fist, etc.). That is also the general Pathfinder Society practice. Here's a Paizo forum post (one of hundreds) that is nicely concise.
However, since there has never been a ruling of impeccable authority on the question, it is ultimately up to your table. To save the usual monk haters the time, I will note that many believe that monk/unarmed stuff is weak enough that allowing gauntlet etc. enchants or even "double dipping" enchants as you propose is still balanced.
Best Answer
No, masterwork ammunition and weapons do not stack
As per Pathfinder's masterwork weapon rules:
Which is in keeping with the general rules for magical weapons and ammunition:
The bonus to attack rolls granted by masterwork equipment is an enhancement bonus, and the enhancement bonus of masterwork ammunition explicitly does not stack with the launcher's enhancement bonus, so unfortunately you get no benefit by using masterwork ammunition if your launcher is already masterwork or better.