Should I buy a Metro pass before going to Paris in a few weeks with all that is going on with the strike? If so what is best way to do this?
1) The strikes do not affect the métro. The métro is run by RATP (Paris Independent Transport Authority). It is SNCF (French National Railways) that is going on strike. The RER (suburban/express métro network) is partially run by SNCF, partially by RATP, so some lines are affected.
2) A métro pass may not be your best way to go. A carnet (bulk discount purchase of 10 tickets) may be better.
And no need to purchase ahead of time. You can get either the pass or carnet easily once you arrive.