Hi, Around Rs. 6000/day (not on disposal i.e. with a fixed itinerary). But I recommend Renting a scooty at Rs. 200/day without fuel. They sell petrol in plastic bottles on roadside. So, availability is not an issue. If you can drive, go for that.
It depends on the vendor to vendor.
Would suggest you to visit the below website for more details, Select the city as Goa on top right corner, and select the dates, you will get your options. http://www.ziphop.in/
Depends on season. I went there in mid oct, although just before on season but it cost me around 5500 for 3 days near calangute area for swift car.
If you are going on season, it may cost less and for on season it may cost upto 1500-2000 per day