How many plants depends on how hot it is. You need to look at something called evapotranspiration rate and water accordingly. If you want a ballpark number, my pineapples in 5 gallon pots get one eighth of a gallon a day and water runs out.
Most drip systems in the hardware store have a minimum PSI requirement. You'll want to look at drippers intended for grey water or well water systems. Something like these: https://www.dripdepot.com/category/drip-irrigation-kits-gravity-irrigation-clean-water-kits I haven't used them myself, though so can't give any more advice then that.
Personally I'd run a PVC line under or above ground and set up a pressurized drip system. PVC is cheap, I added a 100' line last year.
what temperatures are required to grow pineapples? could I use supermarket pineapples to start with? I have seen in youtube that we can cut top of pineapple and plant it. is it how it works?