a) Don't know about it but I think it doesn't have it.
b) Yes multi-information has following options: Clock, Elapsed time for any trip, Instantaneous Average, Overall average, Average Speed, Clock, and option for selecting km/l or L/100km.
AC is very good and Cabin is also quite. Accessories for this model are very common and you can find them easily.
Regarding being underpowered, it is not underpowered at all. It's suspension is according to Pakistani roads. One time I went to visit River Ravi near Narowal. My friend took me through an off-roading track and we were 6 people in the car. When I saw the track, I thought it will be very difficult to reach the river bank but GLi did it easily.
So its a good decision if you go for GLi.