Yes, Jio Phone 2 does have the speed dial.
Yes, Jio Phone 2 comes with a pre-loaded YouTube application. You can use YouTube in Jio Phone 2.
Yes, Jio Phone 2 does have the Google Assistant in-built.
Yes, Jio Phone 2 is a dual sim mobile phone. You can use 4G sim card slot with the Jio sim and another slot can be used with 2G network sim card.
Yes, you can use WhatsApp in Jio Phone 2.