Recently I bought a refurbished PS4 with two games (disc versions, madden and destiny), but I have had issues with the PS4 and I would like to purchase a new one and return the old one. First, will my madden saves transfer over when I log into my other PS4 or will I have to use a usb or cloud service? Second, when you first insert the destiny disc, there's about an 18 gig download for updates and such, will it do the same thing when I insert it into the new console? Third, I also received a code for the taken King dlc and have already entered the code on my PS4. Am I only going to have that dlc on that console? I'm guessing I can't enter the code twice, so I want to make sure it's account bound and not console bound. Any advice on this is greatly appreciated, thank you.
Your data is tied to your PlayStation account, not the physical hardware. Otherwise, a fried motherboard could cost years of time spent.
You need to follow the same directions for upgrading the hard drive in your PS4, except you will be replacing the whole console, not just the hard drive:
You can sync your save data on the cloud if you have a PlayStation Plus account (the one you pay money for each month).
You can sync your save data locally using a USB stick.
You will need to reinstall your games on the new console to include downloading those massive updates again unless you back up to a larger USB storage medium, such as a USB hard drive. Unless you have one laying around, that is a lot of money to spend when you can just have the new console update overnight while you sleep.
Any DLC (e.g. The Taken King) or digitally-purchased content such as buying a game or other app in the PlayStation store as opposed to the physical disc is tied to your account. Once you set up the new console with your existing account and you are connected to the Internet you can go to "library" and select it to download it.
I upgraded my PS4's hard drive very recently and have been through the backup/restore process. It took a while to reinstall and update everything, but the process was very easy, and none of my save games were missing or broken. I have all of my paid content available, including games I bought digitally. The process is not very intimidating and they make it easy even for nontechnical people.