User Manual Breville LAP158WHT Easy Air Connect Purifier

They recommend changing the filter every 6 months if you are using the air purifier 24 hours a day

Yes, you can hit the night button and it switches to a quieter mode with no light.

I got a spare filter from Amazon at the same time I got the Air Purifier unit. Saves on postage, and just in case they get harder to get in the future.

Don't know the dB (athough I do recall seeing them somewhere before I bought it) but on the lowest setting it is hard to hear (wouldnt know it was on unless standing right up close) and at "turbo" setting I prefer to be in another room - but that's just to get the air quickly cleaned for a short burst at the beginning. I don't use the other settings much, but they are much like having a fan on in the room - a pleasant whirr.