Hi,

you need not prepare for army separately if you want to get in the army in technical field,but if you want the job of an army officer in field then you have to prepare for cds,for which you can take help of officers academy Hyderabad,they are an very good institute run by ex army men .

there is nothing to do extra,

the question will be comes from your own departments.

so study your core subjects very carefully,

courses.as part of the suggestion i would adivise you not to waste your degree by joining Indian army after doing B.Tech.but if you are willing then please refer to the emplyment news regularly.

and it is conducted by the government.

Hope this helps

Wish you luck