Cable Size for 100 amp service load center
If (as you imply with the A/C) the service is 120/240 USA-style then 95 feet of 4 Ga copper would be 2.5% drop at 100 amps and thus within the 3% drop even at full load. If it was 120V-only (I don't know that any country actually does that?) then you'd probably want bigger wire. 

Speculating: Local advice may have to do with less-robust supply to the meter than we are used to in the USA, if there is already significant drop on the way to the meter, you may want to minimize the drop from the meter, as you might not have 240V to start with...

Your A/C units would be better if 240V (same power, half the current, 1/4 the percentage voltage drop) if you have a choice. Likewise the water heaters. 

Lights should be trivial if you have no objection to and can get LED units.