Yes! Everything we are providing is just a recommendation. Although if you've never stayed in India before we advise you to be careful, especially with hotel selection.
Bengaluru is a "tech city" and is a very modern and clean city by the standards of India. You should not need to take any precautions outside of normal for travelling internationally. The one exception is drinking water (see below). In terms of cleanliness you will notice a bit more garbage than you are used to, but not nearly as much as many other cities/towns in India. You will see plenty of street dogs, but not many cows in the city.
We do not advise drinking tap water anywhere in India. Bottled water is always recommended. The wedding venue will have plenty of bottled water (and alcohol). Most hotels that cater to Westerners provide unlimited bottled water at no extra charge (or extremely cheap). Make sure you take some with you if you are going out in the city!
Yes, you can eat meat, although outside of western style hotels you are not likely to find beef or pork. Chicken is very common.
If you are just coming for the wedding, then no special vaccinations are required. if you are planning to travel in India before or after the wedding you should consult your doctor as some vaccines are recommended for some locations.
No, he is going to marry Yesurekha it's too late for you.