Spectra S2 pump

Hi everyone I recently got my spectra pump n have few questions... help is really appreciated ...

1) for how long can I use the massage / stimulation n will it effect my output if I use that extra vibration for longer time??

2) any useful tips that would help me in using this pump??

3) when I begin pumping my nipple does not stick to the sides of the flanges but after some time it does rub on the sides... should I go up size on the flanges ??

4) does milk enter in the back flow prevention thing on the back n how often do u all wash all the pump parts??

Any tips to increase milk supply is also deeply appreciated as I’m very low on supply...