Electrical – how should i wire up this 2-way z-wave switch

Too bad I haven't updated answer when I rewired everything - but better late, then never, right? Here are the answers to my questions:

1. White wire is neutral in US in most cases... so it was in my case.
2. Basically, two whites were neutrals for two different circuits. I bought Voltage detector and separated right white wire by turning off circuit for lights - the other white still had electricity running through it so I was able to figure it which white/neutral I needed
3. Yeah, I just cut it, add in neutral connecting from the switch and then put cap on
4. For this you need Voltage Meter, there are quite few tutorials on YouTube that explain how to figure out which wire is which with Voltage Meter.

If the switch has screw terminals as opposed to wire leads you DO have to pig-tail a piece of wire to the splice and then connect that tail to the switch. DO NOT place more than one wire under a binding screw terminal, unless of course it is designed for it. Even in that case it would only be designed for up to two wires.

Do you have a model number for this switch?

Regarding the neutral wires in the box, NO not every wire goes back to the breaker box. This is why you have several whites. One is a feed and the others are feed out to other items on the same circuit. If there is more than one circuit in the box then the neutrals from those different circuit should NOT be spliced. The only time this is not the case is if it is a multi-wire branch circuit (shared neutral).