If you are current using a SSD, then this should work the same. You may need a 2.5 to 3.5 caddy to install in a 3.5 bay. But most new systems have 2.5 bays
The Drive is 2.5 inches. Perfect for Laptops. It can be used in a desktop as well, however I would suggest buying a cradle that allows 2.5 to fin in a 3.5 bay. Or place it in the Floppy tray.
The device will be compatible with your desktop. At most, the only thing you may have to buy is a mounting bracket so it will fit where your hard drives go, but if you don't want to buy one, it's really not necessary.
This SSD uses standard SATA power and data connections and is downward compatible with SATA 2. I would say YES it will work with your desktop. I put them in desktops all the time.
The SSD drive does not need anything else to be used in a desktop computer other than a tray to hold it in the bay where your regular hard drive fits. I was able to use an adapter I had for this purpose. I saw on a youtube video that some just use Velcro to hold it in place.
A Best Buy salesperson would be able to answer questions regarding pricing and availability. If you have a specific product in mind, you can also ask at 888-BEST-BUY.
The default memory space is 500gb for the current console, but I'd like to improve it. So, does this item fit in a playstation 4? If not, which one(s) can be a better option regarding SSDs?
It will fit, and it will work. However, you should reconsider wasting this on a PS4. I would go with a Hybrid drive, since the PS4 cant utilize a SSD at even 50%.