I will be interested to see what the car is like when you get it. I bought one in a poor state last year and have spent quite a bit of time and cash getting it somewhere near decent.
Experiences of the auto:
Its good to drive although as I'm used to a five speed modern auto box on my daily driver the three speed takes a bit of getting used to. First gear is low and third is not very high so motorway driving at 80mph, the engine is at 4,000 rpm compared to the manual version which would be at 3,500.
The box changes pretty smoothly. As you are planning to do, I had all the fluids changed - brake, coolant, diff., auto box as it had no service history.
I don't know whether it is because of the auto transmission radiator which needs cooling too, but the electric fans cut in more often on this than on my manual gearbox one. It doesn't matter what the outside temp. is, after a minute or two at standstill the fans cut in. There is no overheating, though, so I assume its normal.
Fuel economy is not bad, only slightly less than the manual (I reckon it is about 25 miles per US gallon) but I guess you guys don't even think about such things with your cheap petrol

(over here its now hitting the equivalent of $8.30 for a US gallon)