1. yes, having your car washed weekly is actually the minimum recommended number of washes per week, but you would have to use a duster to reduce the dusts clinging on to the paint, here in caloocan where its really dirty what i do i have it washed 2 to 3 times a week and then maintained with QD and duster. Using water can also be an option but i would rather advice you to use a mild shampoo that wont strip wax but powerful enough to remove semi bonded contaminants and road films
2. The advised frequency for well maintained cars is once a month, but since its really dirty in our country you might want to do it twice a month especially if the car is a daily drive. I used to wax my car weekly but now i wax them ever other week.
3. I've tried that shampoo before and i even have some at home but i really can't remember how it fares with other shampoos, as i remember its a bit strong IMO, the turtle wax Ice shampoo is much better same goes with Megs NXT, but as far as i remember its a good shampoo that won't strip wax, that why i kept it at home.
Since this is a BB thread, you might also want to get their input on this matter hehe, lets wait for vince, jeff, paul or whoever to chime in