Mira - any basically, best showers you can buy (my opinion) have a look at Mira Excel.
I have a Mira Excel BSM (bath shower mixer) sits on the bath so no controls/pipes fitted to the tiles, it's then a thermostatically controlled bath tap and mixer shower. Ideal if you have kids. I paid Â£399 for mine, shop around you might get it cheaper.
There's only 2 pipes needed, there's no pipes to the shower above the bath like other mixer showers. No trying to clean behind pipes.
Just had my bathroom tiled, he used a mould resistant grout and added a rubberising compound which allows for slight movement etc.
usually the yellowing of grout is caused by a build up of bacteria that cling to it. get a decent quality grout containing microban technology, available from decent tile shops. a good rule is that if its quality that you are after in your materials, go where the professionals go, don't buy from diy chains.... in the words of graham taylor.... do i not like orange.