Yes, acrylics work great on watercolor paper. You can use them as transparent washes (like watercolors), or semi-transparent or all the way to fully opaque. Because they dry so quickly and cannot be rewetted or lifted as you can with watercolors, you might want to plan ahead a bit. One of my favorite techniques in using acrylics on watercolor paper is to prewet the paper and lay in a transparent wash of acrylics. If you want a soft blend or edge, have a just-damp clean brush handy to softly swab over the area you want to blend or soften. The great thing about acrylics is that, once they dry, they are permanent and you can go over them as many times as you wish with more layers of color without fear of the bottom layers being mixed in and becoming muddy.
I generally begin a painting on watercolor paper by laying in transparent washes of color. I gradually start adding a bit thicker paint, working in semi-transparent to opaque layers to finish the painting. It is a combination I love.
If you look at my gallery website, you will see that most of my acrylic paintings are done on watercolor paper.
You can work on many different kinds of surfaces. Two of my other favorites are illustration board and watercolor canvas. You can choose to apply some coats of acrylic gesso first or not. The gesso will help to seal the surface and make it less absorbant. The paint behaves differently on different surfaces. Explore and enjoy!
I love cooking with wines! Sometimes I even put it in the food!
My website (undergoing reconstruction) http://spechtgallery.com