No, a barrel nut wrench is not included. It uses a 1-1/4" Crow Foot.
Barrel nut, mounting screws, and an accessory rail are included.
Odin Works recommends using their barrel nut with the ODIN Works O2 Lite Free Float M-LOK Forend.
You can not mount an extra picatinny rail at the 12 o'clock position on the ODIN Works O2 Lite Free Float M-LOK Forend.
The ODIN Works O2 Lite Free Float M-LOK Forends are compatible with low profile gas blocks and will not work with an A2 front sight post.
The manufacturer doesn't state if the ODIN Works O2 Lite Free Float M-LOK Forend internal diameter is measured from all points 360 degrees internally. For that information I recommend contacting ODIN Works. However, I would assume the internal diameter at the narrowest parts is 1.6" in order to give customers a reference of what muzzle breaks and suppressors will fit without contacting the ODIN Works O2 Lite Free Float M-LOK Forend. A 1.5" suppressor in theory could fit but will be a tight fit.
The ODIN Works O2 Lite Free Float M-LOK Forend does not utilize anti-rotation tabs. So this forend should fit and function fine. It will include all necessary hardware required to install including the barrel nut.
Inside diameter of this handguard is 1.6"
Pick the rail for the rifle type you are using.
We cannot confirm compatibility because the handguard is meant to accommodate a standard AR-15 direct impingement gas system. It is not necessarily meant to accommodate a piston system with an operating rod. You will need to confirm compatibility with Odin Works or verify with Adams Arms whether they have a list of handguards they have tested.