Actually, energy is defined in the rules. It's Fire/Cold/Lightning/Acid/Sonic. Nothing else is Energy.
Regardless, I do allow, and don't think it's so bad. But RAW does seem to be unclear.
RAW, I'd say this doesn't really work, since you're not supposed to guess at the effect.
Wrong, actually. Negative energy, positive energy, and force are all still energy effects in the game. They are non-standard ones, definitely, and are not covered under standard energy resists/immunities, but they are still typed as energy, because you can still HAVE resistance to them, instead of DR, which is for physical damage.
As for Wind Wall affecting "force projectiles", I would rule that since it no longer deals physical damage, it should no longer be treated as a physical projectile. It can still affect physical targets and requires an attack roll to hit, so the 30% miss chance should still apply, as it should to any spell requiring a ranged (touch) attack, unless the spell creates boulders or the like (eg. Giant's Wrath). But that's just my logic for a reasonable interpretation.
Now, what should happen if the force projectile enters an AMF? Does it revert back into an arrow/bolt, or does it vanish entirely?