It's not easy to tell texture depth in a photo. What I can tell you is back in the day my mom had sand paper texture on all her walls. We took scrapers to it, knocked off the pointy parts then wall papered with a thicker vinyl paper and it worked fine.

You could use liner paper under your wallpaper to give you a smoother surface. It goes on first and then you hang your decorative wallpaper. The liner paper leaves your existing texture intact if you want to go back to paint at sometime.

Sanding will create a incredible amount of dust. There are some sander that vacuum dust as you sand and the air goes through a bucket of water that catches all the dust.

Here is a nice article for removing orange peel texture from a wall.

Depending on the wallpaper material (canvas,paper, vinyl) and the adhesion method (peel and stick, paste, pre-pasted) You could just put the wallpaper over top of the texture. Since you specified that your wallpaper is not thick I would look at removing the texture.