Yes. The Battle Arms Development AR15/M16 Enhanced Bolt Catch is compatible with the Magpul BAD Lever. It will fit all Milspec AR15 platform rifles and pistols.
The lower cost model is cast while the more expensive model is machined from a bilit.
An AR-15 bolt catch is not compatible with most AR-10 lower receivers. You would need to use an AR-10 specific bolt catch.
The Battle Arms Development AR15/M16 Enhanced Bolt Catch does not include a retaining pin, you will be able to re-use your original pin.
The Battle Arms Development AR15/M16 Enhanced Bolt Catch weighs 0.39oz.
No this unit is meant specifically for AR-15 platforms. Unfortunately we do not currently carry it, so you will need to source it direct from the manufacturer.
This does not include either the plunger or spring