If you're using a US carrier device, you're likely limited to T-Mobile, Sprint, and US Cellular (maybe). Those are the carriers that I can think of at the moment, but it's been a while since I looked. Verizon is locked tight, and the last I read AT&T was too. I don't know if the US unbranded devices are locked. Some of the devices made for outside the US are unlocked as well.
Even if you are able to get full root, deleting system apps can brick your phone. It's about knowing which ones are safe to get rid of. And if this phone is like some of the others that I have used (I haven't rooted a phone in some time), you won't actually get to use the minimal space that you free up. System apps normally reside on a protected system partition in the phone's memory that user apps can't get to. So even if you clear some of that, you won't be able to use it for anything else.
Another thing about root is that you won't be able to use Samsung Pay on a rooted device. I've read that some other apps (like Pokemon Go) won't run on rooted devices either.
For handling apps, try a package disabler app. There are several in the Play Store. I use Package Disabler Pro
https://play.google.com/store/apps/details?id=com.ospolice.packagedisablerpro They work by giving you access to the entire system partition, including all of the bloat apps. If you're familiar with root applications, this is similar to the "freeze" function built into root utilities like Titanium Backup.
Disabling (or freezing) apps won't delete them, but they won't run. That means that they're not consuming resources like power and data. Pay attention to the app colors in the app list in PDP. Hit the ? to see the color key (legend) and identify which apps are relatively safe to disable. Be careful though, it's easy to cause yourself lots of grief by disabling something that you shouldn't. Sometimes, the only fix is the dreaded factory data reset.
For customization, try a third-party launcher and a theme. There are lots of themes in the Samsung Galaxy Theme store, and many are free. A launcher will let you customize just about anything on your device and let you make it your own. App drawers, backgrounds, menus, icons and spacing, etc. Good launchers are all over the Play store. Some of the best are Nova, Action Launcher 3, and Google Launcher. Try several, most are free to try.
Good luck.