The answers to this are clear and already well documented on pprune - use of the search function will give you more info.
In summary - the non-faa licence must be VALID - this means not under suspension, wthdrawn or expired. Nothing to do with currency. Currency is irrelevant.
To use the privileges of the 61.75 you need either a current FAA medical or medical certificate appropriate to the underlying licence. You also need a current flight review ( BFR ). When a 61.75 is issued it does NOT convey a flight review ( like a check ride woudl) nor does a foreign currency check count. A FAA flight review is thus required before using the 61.75 and thereafter when using it.