I am using Philips 100/90 on my Santro for more than 3 years. I never had any issues and quite happy with the light. I did change my Verna also recently with the same bulbs. Better dont try out other brands as they dont seem to last as long as Philips. I had tried with Osram but one of the bulb lasted only about 3 months. Same is the case with household CFL bulbs.
All TATA's are prewired for Music System, Fog Lamps, Additional Horns etc. You Don't need to Ideally install any additional Relay unless you are going above the recommended OEM Range...So its more of a plug and play application.
The OEM foglamps are from Minda- and cost around 700 each at the showroom plus Tax.
Outside OEM Minda will cost you 400 each plus tax.
Rates can vary so, consider them as range index.
Switch can be sourced from TATA Dealer or Spare parts shops will cost at the most 300 or 400 for OEM and around 100-200 for Local make.
one can change the bulb to Xenon (HID) to get better illumination on the road....the bulb color can be selected can be 4300k as it will near to yellow light and will be brighter than the normal halogen about 2 times....
The only way to fit big huge fog lamps is to cut the bumper, install fiber(the kind used for car skirts) cut to size and have the fogs inside that.
In the stock location in the baleno bumber, you will have to go for small fog lamps, which as per my experience are not much better than the indicator lights.
You can also toy with the indica option, if they fit then good, otherwise you can try with innova, indigo(round lower fogs)... and so on till you find the right fit.