The Highland Beach is a good choice - one of the better hotels. The Highland Beach has its own restaurant at the back of the hotel which does good indian food - it is a little more expensive but very good. I personally love the Fishermans Cove which is on Beach Road. They do a mean full chicken tandoori cooked fresh for about 2 (and for this you get a whole chicken!). Another great place is the Mango Grove which does a variety of foods. It is also a good place to have a beer or two and watch the world go by. Alexandras is another popular multi-cuisine restaurant, also on beach road. Too be honest, you could ask 20 people for their favourites and get 20 different restaurants - basically you cannot go wrong eating anywhere.
Re the malaria tablets, they are a fraction of the cost in the UK and I do mean "a fraction". You will pay around 15 for a treatment in the UK. In Goa you will pay a few pence. The only problem is that you are supposed to start the treatment a week before you go to make sure you are covered as soon as you arrive. Even if you don't use the local ones this time, if you intend going back I would suggest you buy locally for next time.
Have a great holiday - we go in December for the 5th time and can't wait.
Candybabe