Corel Draw Vector Illustrations

I do oil and acrylic paintings as a hobby. I have now started to use a digital art program called Sketchbook.

How does Corel Draw and whole suite compare to Adobe Photoshop, Illustrator, Sketchbook and other similar programs? I see a similar comparison between Sketchbook and the others mentioned.

I have seen Joseph  Diaz video on vector illustrations and are very good.

What is the purpose of the vector illustration by tracing over a photo and then colouring in the polygons apart from giving a cubism effect? It is very time consuming. Is method used to use one layer only instead of many layers?

I would like to make digital art by the same method of using acrylic and oils paints with brush tools etc. Would I need to use many layers to make different paint effects on each layer to prevent smudging colours? Or can different layers be combined to blend colours without destroying other layers?

The subjects I have interest in are portraits, wild life and landscapes.

I appreciate your reply.