Chetan, to heal a diet high in protein is necessary. Also your daily calories should be a minimum of 2500 daily with a minimum of 64 oz of water. If you skimp it will only hurt you in the end making your recovery longer and much more difficult. Since you mentioned eating is difficult for you, it sounds like your calories are on the low side. With drinking one ensure a day, it isnt even close to being enough to get your body into healing mode.

Make use of the search functions on the forum. There are many many posts full of info that will help with the above questions. Here is a list of easy to eat foods.
http://oralcancersupport.org/forums/ubbthreads.php?ubb=showflat&Number=94621#Post94621