Your best bet is to ask the company to provide the details - they'll have tax boffins that will provide the right answer. The approximate answer is "66.5% will be left after tax", but you'll be surprised to find how often it's lesser than 66.5% left! That's because the actual salary figure ($8000) might be the CTC figure (cost to company), hence the salary might be slighly lesser (say $7500), with the balance going towards all sort of junk (Provident fund? Gratuity? Company car? All stuff you'll have a tough time to recover - if at all possible).
But assuming that your salary is in fact $8000 - you should have approximately $5320 as the salary in hand. I say approximately because the tax is not actually 33.5%, but a slab structure. But given your salary, you'll be basically all at the highest taxation slab.
Living expenses are tough to approximate - but I'd guess if you lead an "expat life" - then about Rs 100000 to Rs. 125000 per month is what you need to budget for. If you are OK
with leading a regular Indian life (for instance no predictability on water/electricity!) - then your monthly expenses might be half that amount or less.
It's really not needed in India - since regular doctors/medicines are cheap and plentiful. What we do have on offer is "hospitalization cover" - for anything that will need you to spend 24hrs+ in hospital. The typical premium for that is going to be something like Rs.6000 or Rs.8000/year.
Feel free to shoot any other questions - and best of luck with your decision. The biggest risk of coming to India is that you might not want to leave