Sounds like a good plan!! Chalk paint will adhere without any sanding. Just put poly over it if you want a sheen, and the top will need several coats. There are many brands on the market, and no matter what they claim, you will need at least 2 coats.

Even with chalk paint it will chip eventually, and gray isn't the best color for your floors or walls. I would keep the table as it is, and replace your pillows instead, with a more graphic pattern that incorporates the white, gray, and yellow. Or paint the walls. The table is the best thing in the space.

Your table top would look nice in a weathered classic gray stain finish and a white flour color for the base. If you decide to sand it, 80 grit is good. Here are some more ideas for you. You might want to go bigger on the pillows. Maybe rattan chairs:

Be sure to post your results!