Different number of address pins

The reference designs in the Nios II kits don't have reset_n_to_the_lan91c111 connected because the MAX part on the PCB is controlling the reset. If you don't have such a setup then you would have to use it. Also I forget if that chip used reset_n or reset (the lan controller in SOPC builder used to export the wrong polarity). So check the data sheet of the lan91c111 to determine if you should throw an inverter on the reset signal or not.

Because the controller is hooked up to the tri-state bridge, those addresses are byte addresses (15..0). The chip uses 16 bit wide data so just use the top 15 bits when you wire it (take a look at the schematic for the Nios development boards and you will see this wiring).