Is it okay to charge the IPad overnight

Perfectly!

More on batteries:

Charge and monitor the iPad battery - Apple Support

Batteries - Maximizing Performance - Apple

iPhone Battery and Performance - Apple Support

Get help with your Mac notebook battery - Apple Support

Yes.

Take a look at this useful User Tip:--> When to charge your iPhone or iPad - Apple Community

Regards

Giulio

Connecting your iPad to its Power Adapter overnight is not only okay - but is recommended. The automatic iCloud backup will only occur whilst the iPad is locked (and unused) whilst connected to both a WiFi Network and the Power Adapter.

Your iPad cannot be overcharged; the iPad will automatically regulate/optimise is charging strategy. In the morning, your iPad will be fully charged and ready for use.

Yes, you can do that.

Your iPad has a smart feature that charges slower or schedules when to charge to make your battery last longer.

Stay safe