No one can tell you chances for SWOP but you have less chance with a PM certificate (that can be taken anywhere in the world and even online) than a Masters. You always have to plan that a spouse may not get a work permit.
I have B.Tech with 20 years experience and if i try for Master or Post graduation in my field, Is it giving high chance for getting study visa and spouse as open work permit? Can i get both visa on same time?
It is going to be incredibly tough to prove that you are leaving a 20 year career and the primarily and I would guess almost sole income earner to start studying again. You would need to show why it makes sense for you to stop studying, move across the world and pay high fees if you are already in good employment.