The tablet comes without a pen. I work without a pen, so I can't judge which pen you should use. I think it can be a normal, commercially available pen that you can buy in different versions.
Presumably the app is not suitable for a tablet. It will be optimised for a smartphone. I also had such problems because
some apps require SMS authentication. Unfortunately, I could not use these apps on the tablet. Or it is simply the graphics, which are only designed for small screens.
That would certainly be possible somehow. But in my opinion it is a very impractical solution! (a tray on a cable...)
Have you ever thought about a Google Chromecast or something similar?
You can actually use any Bluetooth keyboard for this. Unfortunately, I don't know of a keyboard case. But you might be able to find one at the Amazons or on Ebay.
The current version of the Netflix app requires Android version 5.0 or higher. Android version 8.0 Oreo is installed on this tablet, so it is not a problem. Unfortunately, Netflix HD is not (or not yet) supported on this Galaxy Tab. Here you can see a list; https://help.netflix.com/de...
I don't think this model supports MHL which allows you to play on the TV via HDMI adapter.
There are other ways, such as Chromecast. Connect wirelessly.