In my case, rooting was trivial to do. There are an assortment of "one click root" solutions. I used one called Kingo Root. I installed it on Windows, connected my tablet via USB cable, and ran Kingo. Kingo recognized the tablet as a model it knew how to root, pushed the required exploit to the tablet, and Presto! It was rooted.
Whether you
need to root your device is another matter. If the only thing I did with my tablet was use it to display eBooks, rooting would be unnecessary. The stock device would do it fine.
One reason for rooting was wanting to get rid of various things that came pre-installed by the vendor. I don't want the Wild Tangent games store, or the Blio eBook store/reader, but they were installed as system apps and could not be removed by the standard add/remove apps routines in Android.
Another was that rooted, I could set things up to store programs on the external card and run them from there. The scarce resource on the models I have is space to store programs, and I exhausted that within about two days on the earlier model I had before this one.
If the RCA runs Win10, rooting is irrelevant. Windows works differently than Android.
The version of FBReader I use is specific to Android. It will not run on a Win10 device. There
is an earlier version of FBReader that runs on Windows and I have it here, but it hasn't been actively developed in some time.
One concern to be aware of: FBReader does
not handle books with DRM. I don't
get eBooks with DRM, so I don't care. If you have titles with DRM, you will need to install something like the Kindle or Nook apps to open and view them.
(If you use Calibre to manage your eBook library and place books on your device, it can remove DRM using third-party plugins. They are not shipped with Calibre to avoid legal issues, as simply
having them is illegal in some jurisdictions, but are easy enough to find.)
A lot.
It will be a function of the average size. If what you primarily read is fiction, I'd call 500-600KB an average file size. For non-fiction, all bets are off. I have some PDFs, for example, that are in the 100MB range. I do
not try to read them on the tablet. A 7" tablet is ill suited for PDF files in the first place, and a 100MB PDF would take a good approximation of forever to open.
I have multiple thousands of books on the tablet, and that's a subset of the full collection in Calibre on the desktop. I think I've used about 12GB of the card thus far, but there are a few videos, MP3 files and other things stored there as well, so it's not
all eBooks.
The Kindle Fire got interest when it was first released because it wasn't hard to root, and once you did, you had a cheap general purpose Android tablet.
I looked at the Fire back when, but it had no slot to add an external microSD card. That made it unsuitable for me.
You are at least aware you need to do it, and presumably know how.
______
Dennis