Absolutely - there are pre-sealed grouts that you can select from - and many, many colors of grout that you can choose from as well. Take your samples in and hold up the grout samples to the rest - and best of luck to you!

Yes home depot has some, but consider a tile store for a bigger selection. Also, get a color chart and bring it home. The light in your bathroom can affect how the color appears differently than in the store.

tile shops

roozen is right, big box = convenience not the best price