Here are my answers:
1. Which Car is spacious and has good leg room for front & back seats?
Both are pretty much equal - probably Palio is more spacious from legroom prespective. However, the real difference is the boot and no boot.
2. Which Car has the best Driver's Driving Comfort?
Palio - More power, easy to drive, it is a hatch so, slightly easier to drive as compared to Indigo CS. If you mean driver's comfort from personal comfort prespective, both are equally comfortable - Indigo can make you cry for certain controls and operations are not the best designs - like the gear box - it needs to be muscled through.
3. Which Car has the best Front & Back Suspension for smooth travel?
Both have very good suspensions - Indigo has slightly inferior suspensions, but, thanks to the boot, it has better overall balance - so, kind of evens it out.
4. What is Mileage for the two cars?
Palio - 15 in city and 20-22 on highway. Indigo Petrol - 10 in city, 13/14 on highway. Diesel - 14 in city and 18 on highway.
5. What will be the expected selling price for the two Cars after 3 years?
Tuff to say as both are new launches. If Fiat goes as per market speculations and really expands in India, then Palio certainly will fetch you more. If Fiat fails to spread and they have a brawl with Ratan Tata, then, it might not fetch a great sum. My prediction - Palio will fetch you more.
Cheers,
K prasad