The inputs on the NAP300 are XLR single-ended (i.e. unbalanced) - you should NOT use balanced cables here. Note that the NAP300 comes with the interconnects you will need to connect up to a Naim pre-amp and power supply.
As for the speaker cable, a bit more about this can be read here in the forum FAQ ( well worth reading many of the topics in the FAQ);
Note that the NAP300 comes with two sets of speaker connectors - these are the ideal match for the 4mm speaker sockets and should be used.