Yes it is a specific Airtel sim card,valid for a year but also, it was last year 3000rps, that includes dial up for computers,all texts and phone calls.Maybe expensive for a 2 or 3 week holiday but for long term still good value.
If your good with computers (im not) then you could probably do it yourself.But they only charge about 600rps to do it for you.Just take the lap top into the shop with you when you buy your sim card.
As far as the dongle is concerned ,i think the only difference is the distances that the phone will work away from the computer.The futher
you want the phone away from the computer the dearer the dongle.
Im not a whiz kid with computers and i find it very easy to work.
Hope iv explained it well enough.