They homeseer switches are very new. I’m not sure anyone is carrying them except their own site.
http://store.homeseer.com/store/Dimming-Wall-Switches-C42.aspx
As far as all your other questions, yes, association is the key. Association is what allows one zwave device to send a command to another Z wave Device in the same room without having to talk to the hub first. So this is why you could set up a virtual three-way (no traveler wires) that works without the hub.
There are several important caveats.
One) both devices must be zwave. Sometimes auxiliary switches which are intended to be used with physical traveler wires are not zwave devices at all. That makes them cheaper. But then you need physical traveler wires with them.
Two) association only works over a limited distance. I always say “in one room” but it’s actually “one hop” so you might make a slightly longer distance than that, especially for a zwave plus switch. Maybe 60 feet if you’re lucky. If it’s a regular zwave device, it will probably be about 40 feet.
Signal travels in 360°, so you could probably set up a three-way with one switch at the bottom of the staircase and one at the top.
- The device that is intended to control the other device is the one that must support “association.” In a three-way set up typically the master controls the current to the light fixture and the auxiliary controls the master. So it would be the aux that needs to support association.
However, there are some set ups where you want both to have association, it just depends on the exact details. But the switch where you will manually press the toggle must have association if you want that to trigger an event on another device.
- Association will only give you a basic on/off command without the hub. It probably will not give you dimming.
There are brands that you can buy that use their own features, not just Association, that may be able to give you dimming in a virtual three-way without a hub. I believe Leviton’s Vizia series can do this, but check to be sure. Switches that can do this will be much more expensive.
- There are some “scene controllers” which can use preset scenes like “lamp A to 50%, lamp B to 25%” and would work even if the hub was unplugged-- but some of them require that the hub have set up the scenes in the first place which doesn’t fit your example.
So if you want to use something labeled a “scene controller” you have to go deep into the details to figure out whether it will work for your use case.
- Because you only get a basic on/off command without the hub. You will not be able to take advantage of anything that requires “central scene” commands–And that includes the new homeseer double tap and triple tap features.
Summary
Z wave “association” allows you to send a basic on/off command directly from one zwave device to another zwave device that is close by.
You have to have a controller to set up the network and create the Association, but the $20 minimote can do this.
Once the association is set up, you no longer need to have a controller available, which is why you don’t need a hub.
There are some specific, more expensive devices called “scene controllers” which may be able to send a “set level” or scene command but there are a lot of details that go into what works and what doesn’t and how it gets set up.
It’s easiest if you think of zwave association as just controlling on/off for a nearby zwave device, especially if this is just a temporary set up until you do get a hub.