You can get a new nice largeish 2 bedroom apartment with backup generator, swimming pool and gym(small) for about $450/month. You could also get something much more cheaper at $100/month which would be really low. The tradition is that the security deposit is 10*monthly-rent and paid before you move. Also its always month to month so there is no 1-year lease like in the US.
A new decent car will run you $8000 but you could use ezdrive.in or some cab service. Or you could buy a Nano for $2500 (or a second hand car) and get a full time driver for $140 a month. Maintaining a driver is a pain in the butt I've heard. Or you could just use Autorickshaws every day at $1 each way for a 45 minute trip. ($50 a month?) but they are a hassle.
Traffic is THE horrendous pain in the ass. Make sure your not driving at 8:10am - 10:30am or 4:30pm - 7pm.
Cellphone - you can get prepaid with the same number of minutes as Rupees. So 300 minutes would cost you $6. Also calls to the US are Rs.7/minute or 14cents/minute.
Vegetables are cheaper than the US. Fruits are about as expensive as in the US here unless they are in season. But you get exotic stuff from jackfruit to lychees.
Internet is like $30/m for really fast access. And Electiecity about $20/m max. Cable is like $10 for a bunch of channels including HBO.
Clothes and such are about 50% the cost of india for mid-range stuff. All medium-high to high end stuff is the same cost or more expensive than the US (and usually slightly cheaper looking for some reason).
Bangalore is full of pubs and clubs. I dont know about hte dating scene as I've never lived in Bangalore per se.
Interest rates are high. You cna get like 5% in a bank savings account here but I dont know if you can take it back wtih you and so on. You'll have to look that up.
Thats about it.
You should start applying before you move here so at least you have a process started. Also to get a VISA to work in India you might need a job offer. I dont know.
My brother works at zynga (in bangalore) so email me if you have a strong resume and want it forwraded. The decision to forward would of course be upto my brother based on your resume.