I can't quote your post for some reason, nonie, but what I'm talking about is when you go into the accounts and you see Cloud and Accounts. There is a setting on each one to sync particular things. Some are set and sometimes some are not. Sync all things under each account - Google, Sammy, etc. so you get all stuff. Not a backup, this is different, and then when you get the new one DO NOT let everything auto populate. Do a factory reset from recovery before setting up, and then reboot and setup your phone.
Make sure to quickly go into Google Play and turn off "Auto update my apps". You have to be fast with that. Then go setup the rest of your phone. After you setup everything except apps - either Google or Sammy or sideloads. You can start adding apps OR you can sync your Google stuff (no apps) and your Sammy stuff (no apps) via smart switch. Your phone will be super fast with little or no lag doing it this way. It's a pain to add apps one at a time, but it gives you a chance to go "what is that?" and only get what you know you need and watch for lag as you add things. If you get laggy look at which app you last loaded and check out what's going on with it. Sometimes it's nothing more than apps like Ammy music auto-downloading your music or Sammy downloading your synced SNotes. I forgot to uncheck Ammy Music.
It is a beautiful, fast, well-appointed, sweet device that needs to be setup properly. It's easy to do and just takes a bit of time. You'll be rewarded in the end. Trust me. Been there, done that, and love this thing so much more than I expected - glass back, curved screens, and all (none of the three are to my liking). YMMV Enjoy!