Question

1) This product needs an external antenna for WIFI, 3G, GPS or can also work without external antennas?

2) What is the precision of the GPS module?

Answer 1

1) you can deactivate Wifi and router become fully functional without WIFI antennas. You cannot use WIFI function without antennas or you risk to burn your device. Same for 3G. About GPS if you use without antennas GPS just does not show the position.  All base antennas (excluding GPS) are sold with router. You can use other antennas (i.e. external antennas) if you dislike the ones included in package.

2) Till 1 meter (depends on satellites).