I hooked up my humidifier, and everything seems to be working fine, but I was surprised to see how much water accumulates from the drain...what is a normal amount of drainage over ther first 24 hour period, and then after a week/more how much would generally accumulate over a 24 hour period?

There is no "standard" amount of water that will be used.

This is a flow-thru type humidifier, which means water runs through an evaporative pad and air blows over it to evaporate the water and humidify the house.

The amount of water the unit uses will depend on the house water pressure, humidistat setting, outdoor conditions, the condition of the humidifier pad, the temperature of the air flowing over the pad, the size of the house, the number of people in the house, the amount of of moisture-absorbing material in the home like textiles, carpeting, drapes, furniture etc., and temperature in the house. There are other factors as well.

The humidistat should be set to the lowest point possible and still provide some humidification (so you don't get zapped by touching metal objects or light switches). Some stats are calibrated in percent, while others simply have numbers on the dial. If you have the stat set too high, you may see frost forming on windows or around doors, in which case the setting should be lowered.