You can't. You need to have a Facebook account to sign up to deezer, presumably so they can access your friends addresses. No Facebook, no Deezer.
You can use Deezer on multiple common devices not only including mobile phones and computers but also smartwatches like Apple Watch, Galaxy Watch, etc; smart audio speakers like Amazon Echo; smart digital TVs like Samsung TVs as well as cars. For the details, you can take a look at the official page from Deezer. As long as you have a premium account for Deezer, you can stream your Deezer tracks on any Deezer-supported device. However, if you're about to listen to Deezer tracks on an unauthorized device, you will need a tool to help, such as Tunelf Deetrack Music Converter. Tunelf Deetrack Music Converter allows you to download music songs from Deezer and enable you to play them on any compatible device with ease. Meanwhile, you'll not need to use subscriptions to access these songs after you downloaded them via Tunelf. The downloaded songs will always be available and can be played forever. You can give it a try if you're in need.
WiFi usb adapter is a WiFi card.
Deezer was created in 2007.
No you do not need wifi to use the gameboy emulator.
no
You need to download an emulator that supports wifi
no you dont NEED it, but you do need a router(wifi connection) in order to use the internet on the laptop
no
Not all external peripheral devices need a cable. There are a growing number of devices that use wifi (wireless and no cable required). You can use a wifi keyboard and a wifi mouse. There are wifi printers, and so on.
yes...you do ...
not if you use wifi