Hey Abhiind
I am loving it, been 10 days and I have covered 1180 kms.
I was in similar situation pocket didn't allow for 1.6 and was afraid about 1.4 engine performance but Hyundai tuned it very well.
90bhp is more than enough for this small beast. I have not felt once like it is underpowered.
1. Engine performs very well, like 1.6 engine there is lag around 1.5rpm. But overall it's good.
My travel involves moslty city to be specific NH24 and as of now it returned 15km/ltr with AC on all the time.
2. Two things -
a. Electric Adjustable ORVM, Hyundai should have given these in all variants.
b. Something from top trim, reverse parking camera( this is in my mod list).
3. Seat is equally comfortable, one might miss height adjustable feature in base variant.
4. I am not sure about it, did not even enquire as most of them can be equipped from outside in much lesser price.
Hope this helps