1.5V is a nominal voltage. Depending on the history of the cell the actual voltage may vary. The Ahs are the nominal capacity of the battery, i. e. a nominal current can be drawn for a nominal time. With more cells in the adapter a higher current can be drawn. It can also reduce the drop in voltage under load and result in a higher actual capacity. The drawback with parallel multicell adapters is the possibility of currents flowing between the cells when the cells have different voltages.
If it isnīt broken, it doesnīt have enough features yet.