What will happen in my recipe that calls for mustard seed if I used ground mustard instead?

I have a coleslaw recipe that calls for both celery seed and mustard seed. I can only find ground mustard but I found the celery seed. Will the ground mustard make the salad taste too strong? Should Ikeep looking for mustard seed or just cut in half the amount called for?

I have a recipe for crushed brown mustard seed. Can I substitute “ground mustard” instead?

I couldn’t find “brown mustard seed” anywhere. Can I substitute ground mustard instead?