Yes mate you will require help to get the box in and out as like you say it is very heavy.
Best on a ramp using a gearbox jack but up on axle stands is doable.
I can talk you through the procedure nearer the time, but it is very straight forward.
Not knowing how the cars been driven makes it hard to diagnose the premature failure but yes, change the master at the same time because this smacks of return valve failure.
Cheers,
Alex.