Yes, the Devil Dog Concepts M-TAK Side Charging Handle Kit is compatible with any Standard Forged (.223/5.56 size), Flat Top AR-15/M-16 type Rifle Upper Receiver.
The Devil Dog Concepts M-TAK Side Charging Handle Kit is compatible with Forged Mil-Spec AR15 receivers. So if your Alex Pro Firearms using a forged Mil-Spec upper the Devil Dog Concepts M-TAK Side Charging Handle Kit should work.
No, this is only for 223/556