2. Since it's a 'new' tablet and has a 64bit processor then almost certainly need the arm64-v8a. (In theory it is possible the device has a 32bit os but very unlikely)
However going forward I'd recommend using the playstore to install Paratext lite. (As producing the apk's is no longer quite as straight forward as before, as with 9.5.17.X we upload Android App Bundle (AAB) to the playstore, and the playstore creates the apk's and sends the minimal apk to the device)
1. The Android 9.5.17.X is in beta. Most of the changes from 9.5.16.X to 9.5.17.X are internal changes to the android app. But because of these major internal changes to the android app, we are having a much longer beta stage than normal.
One can get the beta version, by navigating to this link while signed in with the google account used on your android device:
https://play.google.com/apps/testing/org.paratext.ptlite
We have a lot of android users, so our main concern is that we don't cause any problems for users who upgrade from 9.5.16.X to 9.5.17.X, which is the reason for the extended beta stage. Other than that I consider it stable. (being used on 70+ device for quite some time now.)
The beta version is currently 9.5.17.44, this will soon see a large jump to 9.5.17.7?, (Which although the large version jump only represents a small amount of bug fixes)