This isn't an area that window cleaners on this side of the forum are going to be able to help you with, which was why Trevor moved it into the other section.
It can be quite a specialised area, but if all they need is a general cleaner to mop and wash the floors that is different.
I'd say charge whatever you see fit, paying the cleaner something between £6.50 and £7.50 seems reasonable, and time and a half on a sunday is ok too I suppose.
It is more what you are going to put on top.
You should be supplying the chemicals and equipment too, and what happens when whoever you get to do the job (not an easy thing I might add) is either ill or wants time off, the odds are the won't want to do 7 consecutive days either, they are sure to want at least one day off a week.
Personally I wouldn't be interested in this kind of contract! Too much hassle!!!
Ian