Couple queries as I am getting conflicting reports

a) If a Centre Zero Ammeter is showing a slight charge what would this indicate? I thought this was a failed battery?
b) With GWPT if for eg it says calculate the winds at 5000 Feet for lets says Central Tasmania, would you work it out based on the 2 boxes that cover "central Tasmania" or would you just use the one box that Central Tasmania mainly covers?
c) Final question. Lets says you are going from A to B to C to D to E and it is all on a 360 track, all points are same distance apart and you know it is going to take you 5 mins to get from one way point to the next, however when you get to B it takes you 6 mins and not 5, therefore the revised time you will arrive at E would it be Planned ETA + 1 min or calculated now at 24 mins?

thanks