i would recomend NOT staking the gas key until you've tested it out. once you have a positive result (if you do) THEN go back and stake the gas key.
i would NOT rely on any threadlocker to hold your gas key screws in place - and if one of those comes loose, it could very well cause a stoppage that will require destruction of either the charging handle or possibly even the entire upper.
a guy on the blackout forum had a handguard screw get into his charging handle above the BCG and ended up having to cut apart his brand shiny new $250 Seekins Precision upper.
you can see the screw in the pic.