Yes, the Sony A6300 records internal UHD 4K video at up to 30fps with full pixel readout and no pixel binning for high-detail footage.
The NP-FW50 battery provides approximately 310 shots when using the viewfinder or 400 shots when using the LCD screen.
The A6300 is dust and moisture-resistant but not waterproof. It can handle light mist but should not be submerged or used in heavy rain without a housing.
Yes, you can use Canon EF/EF-S lenses on the Sony A6300 using an electronic adapter like the Sigma MC-11 or Metabones Smart Adapter.