Yes, Versafine is perfect with any water-based colouring medium (markers, inks, paints, water soluble crayons etc). It's an oil-based pigment ink so the oil means it resists water just fine.
Any embossing powder will stick to Versafine as far as I know. I tend to use detail embossing powder as it gives a smoother finish and works well with just about any stamp. Ranger is a good brand and if your friend is shopping for you in US it should be easily available.
Hope that helps!