I have a confession: I am a layman when it comes to networking hardware.

I have some basic questions about wifi Internet. The venerable experts on this forum, please help!

I have requested Airtel to install a new Internet connection @ my home in Gurgaon.

1) What is the difference between wifi/router? (just looking for a 1 min. answer as a layman, not the detailed explanation like that on Wikipedia)

2) Does Airtel sell the modem/router or does it just rent it against a one-time non-refundable deposit?

3) Is it advisable to buy a modem/router from a third-party, instead of renting/buying from Airtel?

4) What are the minimum technical specifications that I should check, if I decide to buy it from a third-party? Will TP-LINK 54Mbps wireless router TL-WR340G router allow accessing Airtel Internet (it's the cheapest available online and I am a penny pincher)?

5) Is TP-Link a reliable brand? If not which one is most reliable?

6) Any other things that this dummy should know before spending on wifi installation?