To you first point yes, if you winterize in a cold climate. The Piedmont region in NC where I live sees mild winters so given the limited space I chose the horizontal position. I haven’t seen where Oliver installs them but I think vertical. To you second point yes, when charging, the pump must be off and one water fixture open thus inert. I started with 25psi. Per the instructions it should match the pump psi but not exceed it. Instructions also say the pressure should be released when not in use. The braided hose is better per the instructions to further minimize vibration/noise. However, though someone else said the shorter the distance between the pump and the accumulator the better, the instructions say it doesn’t matter and the accumulator can be placed anywhere in line on the pressurized side. Bill used the provided coupler but also had to raise the accumulator to be inline with the pump. Though I suppose without the extra hose there is less vibration. I wanted the valve on the easy to access side. I am just happy I installed one and will not hear my water lines chatter anymore! Hopefully.