hey there
I'm a final year student at Warwick and I lived in Rootes in the first year. First thing..its great, you will have the time of your life, there is no other halls that can even compare. Don't worry about the bathroom sharing; the cleaners are very good and will come round in the morning. There will be one shower per kitchen at least, and two or three toilets and then two baths. All these are in separate rooms at regular intervals through the corridor so all get used pretty much the same amount. They are not minging. The showers are all clean and so are the tiolets, and to be fair hardly anyone ever bothered to use the bath tubs cos they just took too long, you wanted to be out there with your mates having fun. Worst case, and this has happened a couple of times, that there is someone in the shower when you want to use it, probably at peak times, then just walk to the next kitchen along the corridor (about ten seconds, no lie!) and use theirs.
As for single sex, the only place that offers this is the top floor of Cryfield but I would avoid Cryfield at all costs. Far too many people per kitchen, and far too small and far out. The only thing its got going for it is the common rooms but then they are great.
Hope this has been useful.