Borewell troubleshooting in Medavakkam, Chennai, Tamilnadu : Yield validation & pump selection:

I dug a bore well in Chennai, Medavakkam area. Rocky terrain starts from 5 feet depth. Drill size is 6". From my bore well spot, around 75 feet distance at southern and western direction bore well dug 150 to 200 feet is giving good yield of water. At one location water was available from 18 feet and drilled up to 150 feet.

In my case, as per the driller there was very slight water source at 50 feet depth and after wards dust cloud was coming out till the depth of 250 feet. After that dust cloud stopped coming not but no water out flow. We drilled up to 300 feet. After reaching 300 feet, driller waited for one hour, picked up the drill pipe by 15 feet again lowered it. At about 10 feet depth water droplets started to come out when the driller started air blow. Driller packed and left. He just told us to use compressor pump and did not elaborate. I am unable to proceed further due to lack of guidance.

My questions are:

1. Will the bore be usable or it is a failure?
2. I am afraid, after spending another 20 thousand for compressor and pipes it may prove to be in vain. Is there any way to ensure productivity prior to pump purchase and installation?
3. If I have to buy an air compressor, should I buy a 1 HP regular Air compressor or 1 HP mono block Air compressor or 1.5 HP mono block compressor. Which is proven to be reliable?
4. One more option to drill exists in my plot (due to space & vaasthu restrictions), is it favorable to sink another borehole?