Pari,
There are several ways to wire limit switches, but most people wire them all in Series with NC contact of limit switches.
Here is a webpage that explains this in detail
Wiring home and limit switches
Keep in mind if you are planning on using the home switches as limit switches you can't wire these in series. But the reason for two wires is you have two contacts on each switch the Common and the NC connection. You could actually loop a single conductor from contact to contact all the way around your machine. Do to noise most people keep these in cables with a copper mesh inside that is grounded at one end to shield these signals from noise. For each higher noise immunity many people have the limit switches all in series that operate a 24V relay where the contacts are used to interface to the BOB (Break Out Board). This ensures that low level noise will not impact the signal which is 24VDC, and the interface to the BOB is very short wires from the relay, one to ground the other to the Limit Switch input pin on the BOB. If you have a controller picked out we can explain exactly what you have to do to get things working correctly.
Russ