Yes, the suitable printer cartridges for the HP DeskJet 2820e are indeed the HP 305 and HP 305XL series. - For black printing, you need the HP 305 or HP 305XL black ink cartridge. - For colour printing, you need the HP 305 or HP 305XL 3-colour ink cartridge, which combines the colours cyan, magenta and yellow. The XL variants offer a higher page yield and can save costs in the long term. Multipacks containing both the black and colour cartridges are also available.

Yes....I'm using it with my IMac, iPad, iPhone with Sequoia 15.

The printer is compatible with macOS from version 10.14 Mojave, including macOS Sequioa 15.6.1. The HP Smart App, which is supported from macOS 10.14, is required for use.

Neither. But don't buy the thing. Connection problems again and again...

Operating system compatibility with macOS High Sierra (10.13.6) is not fully supported as HP Smart for Desktop requires macOS 10.14 or higher. However, the printer can be used via AirPrint if it and the Mac are on the same network. This allows printing without additional software, but with possible limitations with other services such as ink subscriptions.

Hi , the printer has never worked properly, and never printed.. very disappointing we did it according the manual and it’s just doesn’t work.

Unfortunately I can't answer that. I just print. Don't need it often.

Wireless here only refers to data communication via WLAN and Bluetooth; a mains connection is required. Yes, we have this type of privacy screen, see here: https://www.galaxus.ch/de/s4/producttype/sichtschutz-2077

It is actually only designed for Bluetooth! Very easy to install with HP Smart as a programme, even on a mobile! But it would also work with a cable (you would have to buy it separately)