YouTube will never be simple to install because Google charges for API based searches. The add-on embeds pre-configured API keys but these have a limited free search quota per 24h period and Kodi has a large userbase so the quota is exhausted within minutes of resetting. The cost of providing paid-for 'free' search for Kodi users would require considerably more revenue than the income Kodi generates from t-shirt sales and public donations. Kodi also has an open-source add-on ecosystem so if we funded API keys in the YouTube add-on, they are not secure and will be instantly stolen and reused by other apps and services (this already happens with the pre-configured ones) with their quota consumption charged to Kodi. If you want easier Google services, the only realistic option is to use the native apps on Android, as then Google provides free access to its own services because "If the service is free, You're the product" is one of the foundation principles of their business model.
For BT problems; delete the device and then redo pairing and (separate) trust using bluetoothctl from the CLI over SSH and see if that then works better. Headphones normally need pair/trust relationships.
If multiple phone apps aren't working, perhaps:
- There's a general issue within your network, e.g. multiple routers and incorrect subnet routing
- Common security or network settings on the phone, e.g. VPNs which route traffic down a tunnel
- There's an issue with config/settings on Kodi - I'd ask for debug logs but they're unlikely to show anything useful