Dooney & BourkePebble Grain Leather Women's Crossbody Shoulder Bag Purse Handbag

What’s the size of this bag?

Are these real?

This seller sells at much lower price, is the bag authentic D&B?

I see this purse comes with a dust bag (which I hope to purchase later). My recent other purses did not. Do only certain purses come with dust bags?