Nothing bad can happen. VOOC Charger also comes with 2A output and Oppo F5 also comes with 2A output. So, it will not harm your phone. But there will not be any change in the charging speed.
No. Oppo F5 does not have the Vooc charging but it does come with 2A output power charger and it has Dual Channel RAM which helps to charge the phone faster.
Oppo F5 has Accelerometer, Ambient Light Sensor, Digital Compass, Proximity and Fingerprint Sensor.
Yes, Oppo F5 does have the multi window support.