Mike, maybe someone more knowledgeable than me can give you a more definitive answer, but my guess is that a Z1000 is fine for running a PS3 locomotive on a modest-sized layout.
I also think that starting with the DCS Remote Commander you have is probably a very good way to start out with DCS.
I got the same Remote Commander about 7 years ago and never used it. I got it because it came with an MTH train set that included a CSX PS3 diesel, and a few freight cars. At that time, I was only interested in the trains that came with the set, not the DCS Remote Commander.
The way I got interested in DCS is through running LionChief Plus (LC+) engines using the LC+ dedicated remote units. I was, and still am, very happy with the user friendliness of running LC+ engines using the remotes.
Then, I gravitated to DCS because I had several PS2 and PS3 locomotives, and wanted to run them like I run my LC+ engines using the remotes.