Two models are available in market (as per my knowledge) the 4GB and 250GB, both can be modded.
There are two ways of modifying XBOX360s:
Software Patch: Safer and later you can uninstall that patch for online gaming, there are different patches, the latest one is LT 3.0. The problem with software patch is that you need games according to their regions, that old NTSC / PAL issue.
Hardware Patch: They install a chip in XBOX called JTag, and then it's called JTagged Xbox360. The benefit is that with JTag you can copy games in your hard drive and X360 becomes region free, so you can play any game. The disadvantage of jTag is that you can't go online.
Price of copy games are around 80Rs to 150rs depending from where you are buying and new/old game.
The price of XBox360 250GB Version with Kinnect is around 45k, and 4GB is around 38k (not sure about them).
And yes you can attach X360 with Computer LCD, there are some additional cables / connectors which you can buy and they won't cost more than 1000Rs (500 - 800 is my idea).
If you are planning to buy, then go for 250GB version, as the new HALO can't be played on 4GB version due to some extra content and if you wants to play multiplayer by going online.