But does the harmony one already have built in commands? Also, can the dimmers act independently with one another? Turn one off while not affecting others?
I am not familiar with the built-in commands of the Harmony One. I understand some harmony remotes come with (or can be configured with) X-10 commands, which might be well suited for your needs.
The point being, the IRLinc does not care which buttons or commands you use. It simply learns whatever command you selected, whether volume, power, channels, or any other. It is up to you to decide which you want to use.
Is the Harmony One an "activity" based remote, like most Harmonys? Can you create a "lighting" activity? What was your intention?
Yes, the dimmers can act independently, if that is what you wish.