RE: VSD pump with accumulator tank?
The accumulator will be useful with the new pump.
The HW heater will stop dribeling with a place for the pressure to go.
The FW pump will also stop "softer" , which will extend its life.
AS an Offshore thinking guy (even tho we don't get there often enough ) I prefer to Hard Mount the FW pump, so I hear it run , esp at night .
Blowing the FW tank doesn't matter much on inshore cruises , but old habits die hard.