A:AnswerHere is a link to an HP support document on changing the ink cartridges on an HP OfficeJet Pro 9015 all in one printer:
https://support.hp.com/us-en/document/c06191540
A:AnswerI’ve had this printer serval weeks. Haven’t printed photos yet, but it does scan on both sides. It will print on both sides, but letter size only. Not familiar with envy 7855. I’ve been working from home and it’s a great printer, met all my needs.
A:AnswerYes, you can scan multiple pages using the document feeder on the top. Use the HP Smart app that communicates from your phone to printer with low level Bluetooth.