Stay at Trident, Nariman Point. Walk to Colaba along Madame Cama Road or through the Nariman Point Business District. See the Vidhan Sabha building, the state's legislative council, proceed along Band Stand, no bands perform here though. Take a diversion to the left along the Institute of Science, the Courts, the University of Mumbai, the Rajabai Tower all built by the British, lovely architecture, return to Regal, visit the Gateway of India, walk along the sea face, return along Colaba Causeway...A brisk walk covering all the above is doable in 30 mins but if you have the time & inclination, it is good for 3-4 hrs including several photo stops & purchase of souvenirs etc including a lot of bargaining.

Most Good hotels have a SPA..you can have a massage for the body at the SPA.

You should ask your hotel, I didn’t shop much, I found I can get a better deal in USA. Everything was poor quality and tailoring, they want to charge a lot for junk. Good luck. We purchased items to find out later it was all fake. Be careful of what you buy.

While there are a few shops adjacent to regal theatre, my suggestion would be to buy “tailor made” leather jackets from Dharavi! This is the best option if you are really keen, want value for money(of course these are not branded jackets) and most importantly, have time!

it's on a side row just very close to presidency radio club close to the fire station

Book Uber. Cheap and best

You can just pay for a pre pay taxi at arrivals. There is a payment desk and it's a set price so you don't have to haggle! You can have AC or non AC. It may be very slightly more than the usual black and yellow cab but the set price and ease makes it worth it

depends where your hotel located? with a good pair of shoes one can walk around as see the sights, gateway of India, Flora Fountain, Museum, marine Drive, HighCourt, Rajabai clock tower etc