Hi Steve.
I have been in touch with one of our branches and this in the information they gave me.
Depending on what the floor is ie,wood or concrete the adhesive and the grout would differ.Limestone needs to be cut with a wet cutter not the standard cutters on runners.What ever the substrate is a rapid adhesive should be used as some staining could occur if a normal setting adhesive is used,plus the adhesive should be white if it is a light colour stone as this could bleed through.Ideally rapid set flexible white would be used on concrete floors and fast flex white on wooden floors.The tiles would need sealing once fixed,prior to grouting.Lithofin stain stop is very good,give them one coat once laid and then a second after grouting and this will help protect the grout from staining aswell.Superflex w/j grout by bal would be the best grout to use on the floor on concrete and on most wooden overlayed floors,on a single layer timber floor a bal w/j grout with gt1 grout admix would be more flexible and the better way to go.
Hope this helps.
Cheers.