A viable concern if you wanted to put it public-facing. If you only care about syncing when you’re home, though, you should be able to host it perfectly fine just not giving any pathways in from the outside world.
If you wanted to use the Android application, you would have to learn about TLS certificates anyway, because it doesn’t work without HTTPS.
It’s been a long while, but I believe you just export from Bitwarden and import into Vaultwarden.
Only if you’re using the Android app or the web browser plugin, the actual core system does not.
They could lock Bitwarden out tomorrow and Valtwarden would still work fine.
Then people would just have to write specific application and plugin if they wanted to continue to use it with no change.
The web interface would be fine.
I’m personally using Let’s Encrypt and duckdns.org for a completely free solution.
Currently only hosting everything on my local network though with VPN to access when not at home.