Lived in India for 2½ years. Mostly in Gujarat, which is primarily vegetarian, but also travelled around Delhi, Rajastan & Maharhashtra. Would echo most of the comments above, ie it's not as spicy as often served in the UK, unless specifically asked for. Eat local dishes, rather than as Tight John McVeigh is a tit says, hashed western dishes. One of the few times that I had stomach problems was caused by a Dominoes pizza!
As regards water, make sure the seal isn't broken and stick with the main brands, Bisleri, Aquafina etc. Also don't forget to use bottled water for brushing your teeth. As regards Ice cubes, then no issue in the main hotel chains but be careful at some of the tourist spots from vendors outside.
Out on the road there is next to no chance of a toilet having toilet paper, so keep a bog-roll or a packet of tissues with you. At service stations etc. then quite often it'll be Asian style squat toilets, although if there is a disabled one, then it'll be a western style one.