I love building this stuff myself because I learn a lot doing it. You didn't ask about this, but I'll mention there is an excellent book on Ethernet that I found to be both easy to read and very informative, it's this one:
http://www.amazon.com/dp/1449361846
So back to your question: The camera you selected looks good, I like that it's Power over Ethernet and has IR LED's so you can see what's going on even if it's pitch dark. It's also nice that it's 1080p, although analyzing HD frames for motion uses a lot more CPU. If I ever upgrade to HD I will definitely consider this camera.
"source type of ffmpeg" just means in Zoneminder, you select "ffmpeg" from a drop-down list box of four source types. I'm looking at my Zoneminder and see the four choices are local, remote, file, and ffmpeg. So that is what the reviewer means by that sentence.
Regarding your computer, it's hard to predict how it will perform. But there are ways to configure Zoneminder to tailor the amount of processing to match what you have available. The two that I use are limiting frame rate for analysis, and limiting the amount of area in the picture that is analyzed, so that you ignore areas that are not of interest.
> It is actually impossible
802.3-2015 40.1.1:
> The following are the objectives of 1000BASE-T: > ... > d) Provide line transmission that supports full and half duplex operation
Also, this Interpretation Request kind of addresses the issue.
> Auto-negotiation signaling is used ... to negotiate that the PHY is capable of supporting 1000BASE-T half duplex or full duplex transmission.