[Galaxy Note Pro 12.2 Q&A, Help & Troubleshooting] firefly6240:
Just thought I would clarify a bit here, I know how confusing it can be coming from windows, I made the switch myself not so many years ago and had a lot of the same questions.

to explain root, the closest comparison I have imperfect as it may be is that root access is similar to windows admin access.

the noticeable difference in a lot of cases is what comes pre-installed.

for example in windows if you have an admin account it automatically unlocks access to the command prompt which was already pre-installed.

in android root access gives you the option to use a terminal but often one is not pre-installed, in fact even a file manager is often not included.

this is actually not a limitation of android so much as a limitation put in place by the specific device manufacturer as to what comes pre-installed.

for example a lot of cheap android tablets running google AOSP (Android open source Project) code actually do come with terminal apps and in some cases even come pre-loaded with root access.

in comparison a lot of more well known devices do not come with this pre-loaded to prevent people from breaking things. (For a windows comparison, its hard to delete the system32 folder without admin access, a file browser and command prompt right?)

As far as samsung abandonment, its a bit trickier there.

Basically what you would normally be used to is the Microsoft scenario.

1. Microsoft - Microsoft makes the OS but it runs on hardware made by others.

a. hardware issues go to the hardware manufacturer for as long as they support it.

b. OS updates are handled by Microsoft, they have more or less full control of the OS as it is closed source.

2. the Samsung Scenario - The hardware is made by the manufacturer, the bootloaders are locked, the OS is made by Google and then tweaked by the manufacturer.

a. all official updates come through the manufacturer (In this case Samsung) after google releases the open source code, samsung then alters it as they like and then they release an update.

b. Samsung is the sole support for the hardware and software as google no longer supports the software for the most part after its been altered.

c. it takes a lot of time and work for samsung to develop an update and push it out and then deal with all of the issues that come with updating the OS.

d. its often easier to leave a device that comparatively very few people bought on an OS that they knew was usable rather than spend all the time and money updating it and dealing with all of the related issues.

With that in mind this tablet has been out for about 2 years now which is a huge amount of time for this type of hardware.

All that being said Samsung very recently released the update to android 5.1.1 for this tablet

so it is definitely not abandoned yet, in fact its had more attention than even other devices by the same manufacturer but I suspect 5.1.1 will be the last official update we see.

if you have one of the note variants with an unlockable bootloader as well as a bit of time on your hands I would very much recommend trying a custom rom if you are worried about samsung abandonment.

you may have to try several different ones though, as you'll find a mix of roms that may seem almost half baked, more alpha release style but are cutting edge (I like those ones myself) to roms that are even more stable than the original.

My apologies if some of this is redundant information, I just thought I would throw in my two cents in case it helps :)