Battle Arms Development states that these gas tubes are compatible with the AR15 and AR10 platform. Pistol 6.6875in, Carbine 9.8in, Mid 11.75in, Rifle 15.125. If you wanted more information, I would recommend reaching out to the manufacturer directly.
Unfortunately no it does not.
Yes, your barrel should use the rifle length tube.
Yes, you will need the mid-length gas tube.