In days gone by I used to mix celery root in with potatoes for mashed, up to half and half. Nowadays I do the same but with cauliflower instead of potatoes. But as you don't like cauli that wouldn't work here. I've never tried celery root mash on it's own, but would think that it might work well. I would add in some roasted garlic as well. Celery root tastes, to me, like a mild flavored mix of celery and turnip, so perhaps adding in some mashed rutabaga or turnip might be to your taste. I've never tried a "potato" salad with celery root, but have successfully used it in other type salads so probably it would also work in what you have in mind. My German husband introduced me to celery root when we first met (and I introduced him to stalk celery, which was not known in Germany back then). A note for prepping celery root: like potatoes, celery root will darken in color readily if not cooked immediately, or put into acidulated water.