Hey,
be careful selecting the wifi router. I am not sure if reliance gives ethernet cable(called RJ45) or a telephone line (RJ11). If your reliance connection is going to be a ethernet cable like the above people said, your selected router will not work. Try to understand the difference and choose the right equipment before you buy.
Ethernet cable link:
In this case you dont need an adsl modem at all. you will be given an i/p address (either static or dynamic) and a lan cable. You have to connect this cable to your computer and then you will become a part of the isp's WAN network which is already connected to the internet. So now, you will be able to access internet(after authentication) through your isp's gateway. Remember you will not get a internet ip at all in this case. (255.255.255.255 ip). ISPs like spectranet(internet only isps with no voice connxn) give this type of connection.
Telephone Line link:
In this case you will be given a telephone line which will be split for your voice telephone and modem. You will NEED an adsl modem to connect to internet. your modem can be configured to automatically authenticate and connect you to internet when it is on. In this case you will get a proper internet ip. ISPs like airtel,bsnl etc give this type of connection.
Generally wifi routers available in the market cater to one of these two only (atleast the lower end ones). If you have RJ45 internet, look for a router with, one RJ45 WAN port, 4 RJ45 LAN ports, and wifi. If you have RJ11 internet look for a router+adsl modem with one RJ11 WAN port, 4 RJ45 LAN ports and wifi. If you look for a device capable of handling both be prepared to spend more.
The other features you can look for in a router is,
Gigabit LAN ports (high speed lan)
Dual bands (high speed wifi 'n')
USB 3G Dongle support
VPN Server
Printer Sharing support
USB Storage support
Automatic torrent downloading feature
Inbuilt FTP server etc the list goes on...
My suggestion is, just buy what you need NOW. Dont be so much futuristic.. because technology will keep evolving (just now wifi 802.11n became the standard and 802.11ac and ad are evolving now). Or else you will end up spending too much money. Hope it helps.