Hiya
You've got some good pointers here, just thought i'd add some too..
1. As already said it's going to be hot. Really HOT, temperature wise maybe it will be 'Vegas' hot i.e up in the 100-110 F, but it's also going to be dusty, dirty, smelly (sometimes!) sweaty hot too. Of course, if you do end up spending most of your time in the hotel or at Air Conditioned places, you'll find it easier. It's when your out and about in the hustle and bustle during the day you've got to be prepared for the hot temperatures.
2. Go with an 'Open mind' - You'll see extreme poverty, possibly some disturbing sights of 4 year old kid beggars with missing limbs etc all begging from you. However much it's a painful sight, try not to be tempted to give them money, it doesn't go to the kid/beggar moreover to the organised crime/beggar controller/pimp type in that area. Excuse the locals if they stare at you, excuse the local boys if they slightly harass you, of course if it ever gets worse, seek the police etc - the likliehood of that is stilly very low though - be a little more vigilant at night though, and as you'll be with your husband, you should be absolutley fine. India is a beautiful country, but in stark contrast there is alot of corruption, poverty and lack of infrastructure.
3. Don't take alot of your best clothes etc - get cheap and cheerful stuff before hand so in case you climb into one of those stupidly high step buses, or catch on a exposed area of a rickshaw etc etc you won't mind so much.
4. Most of the hotel staff will speak English, so any requirements there should be easily sorted. Out and about, you possibly will come across locals and shop owners etc who speak English too - many of the locals who don't speak it, will simply smile and shake their head in a figure of 8 at you !
5. Worked for me - Try to stay away from roadside cafe's or 'Dhaba's' as they're called, street food carts, people cooking on the side of the road etc etc. Some of the stuff is delicious, but I'd rather forego a few seconds of great taste rather than have hours of agony at the other end !!! - Stick to food made at the hotel, and / or - if you find a nice clean restaurant that 'should' be ok too! - For me it all worked as I ate mainly at where my family where so it was all home cooked.
6. If you see bottled water - stick to that, Don't be tempted to have the local water as you'll probably end up sick. If I remember correctly, the bottled water which is available throughout India is called 'Bisleri' - there's probably others too. One thing to watch out for is - to buy it from what looks like a reputable outlet/shop. Famous trick of course is to fill the bottles up with tap water and re-seal them and charge you full price. Inspect the seal, if it looks tampered with in anyway - reject it. The reputable sellers wont mind at all, but they do buy genuine bottles. It's the street sellers and the side sellers you have to be careful of.
7. Make sure you have comfortable and good quality shoes for walking in.
8. if you do get the chance to wander around exploring, I'd suggest giving the ipod etc a miss and just have a camera instead - less to go missing, break or be stolen - especially if you get caught up in a rush!
9. Look up a book called 'Put your best foot forward' - 'Asia' by Mary Murray Bosrock - it's aimed at 'white western business people' visiting countries in Asia and gives a great humourous and serious view on the ways of each country and what to do/say.
Lastly - enjoy yourself! I'm almost jealous, I haven't been 'back home' since 97! and im well overdue a visit!
Hope the above helps - if you have anymore questions, drop em here and I'll see if I can answer or if the 'Geeta Meister' can clue you in!
cheers! DtM! West London & Slough UK!