For the VISA, I would ask the specific question to the US Consulate and get
a written answer. Provide them with the name of the training facility, indicate that the facility is TSA approved and you'll apply as soon as you have confirmation from them, and that the total amount of training would be limited to xxx flight hours and yyy hours of ground school over a 2 week period only.
My guess would be that, provided the training programme would be a 1-2 week finish up at a part 61 unit, the B1/B2 would suffice for them, assuming it's valid for 10 years (i.e. until 2020).
Now, as far as the FAA PPL itself is concerned, indeed you do need
- FAA third class medical
- FAA written test passed (I don't think there is an authorised centre near India, so would have to sit the test in the US near your flight school), although with your flying experience, studying for that wouldn't be too hard.
- FAA oral exam, which is hard. Reading the ASA book is a good start there.
My guess is that it would take you some non negligeable amount of regulation study (assuming you're familiar with all the other topics) and that this might be quite an effort if you then don't have a direct use for the FAA PPL.
If you're only out to get the long cross country, I would follow the same strategy as regards VISA, TSA etc... That wouldn't take more than a week with aircraft / airspace familiarisation. And the probability that the Embassy people would say yes goes from 75% to 95%.