Firstly Its not an ideal time to visit Dubai for tourism. It will be too hot to enjoy anything.
Visa cost is approx. 12K. You only need to give scanned copy of your passport and photograph, it will take around 2-3 days to get visa.
Its better to get visa and look for hotels on booking.com. This time of the year you can get hotels at very reasonable rates.
If you can share exact timings, number of people and your budget then I might suggest some places to stay and things to do in Dubai.