Which technique was used to paint the picture? Recently I saw the following drawing on Etsy and I was wondering if I could do a similar one in acrylic:

 

Do you have any idea/tips how the background was done? At first I thought it was achieved with a spatula. But now I don't believe that anymore - there are too many color accents which can't come from a spatula.

Therefore I would love to hear your ideas or tips on how I could repaint this drawing.
My specific questions are:


How would you create the background (technique)?
Would you texture the canvas before (structure paste) to give it a bit more depth, or would that be too much?
How would you do the vertical "lines/sprinklers"? I could imagine that the paint is too thick to press it directly from the tube onto the picture like this and therefore I have to thin the paint down before making those stripes?
Would you do something different / is there something in the picture that bothers you?


Link to the images

I would be very happy about suggestions and tips! :)
I believe the background was created by the use of randomly layering acrylic paints from darkest to lightest on the background canvas using something like sea sponges, waiting for each paint layer to dry, then adding the next lighter color. Turn the sponge frequently &amp; use different sponges as well so that you get more random patterns all over. Given that this is acrylics, you may not have to wait for the paint to dry; it won't mess up the layer below like watercolor would. 

The "lines" definitely look like slightly thinned paint dropped on and the canvas tilted to allow the paint to run in a line.  A spatula knife may have been used to pull the paint into lines as well - use it to put a small dot of slightly thinned paint on the canvas, tilt the canvas if not already tilted, and pull the spatula knife towards you and/or in a downwards direction in a relatively straight line.