wingman's page

3.5 included the same special line for MWF yet also had improved MWF and greater MWF as feats with identical special lines respectively.

This feat replaces the Two Weapon Fighting feat for creatures with more than 2 arms.

One could argue that replacing the TWF feat for the character does not adjust the prerequisites of feats he does not have.
Without clarification from Paizo no definite answer can be given, so house rule it. But don't be surprised if your DM shoots down a 6th level fighter with 8 attacks.

H. By the special line MWF replaces TWF, but it doesn't specify it qualifies as TWF for the purposes of prerequisites so you wouldn't qualify for improved or greater TWF. The purpose of the by-line is to clarify you can't take TWF. Shouldn't be a problem since having MWF gives you the equivalent of improved and greater TWF, granted at a bigger penalty but also at a much lower level.

The ratfolk swarming trait reads:
"Up to two ratfolk can share the same square at the same time. If two ratfolk in the same square attack the same foe, they are considered to be flanking that foe as if they were in two opposite squares."
What if the ratfolk are acting on different initiative counts? Is the first ratfolk considered flanking prior to the attacks of the second?