ARC = audio return channel. If you connect devices to the TV or use the TV's sources like antenna or smart TV apps then it can send the sound back ti the sound bar or receiver through the HDMI. However, it does not always work correctly because depending on how HDMI syncs sometimes it only gets a stereo signal. Also, ARC does not send the lossless formats like True HD and Master DTS. To use ARC you have to turn on CEC. You are much better to connect all your components to the sound bar and then connect one HDMI to the TV from the sound bar. Even if your sound bar only has one HDMI out I wouldn't use ARC. I'd run an optical cable back the the sound bar instead of ARC. I guess that is why we see so many sound bars with optical inputs and no HDMI, they don't want to deal with the ARC/CEC headaches.
CEC = consumer electronic control. In theory it is supposed to switch all your inputs, control the volume, and turn off equipment not being used. So if you turn on your blu-ray player for instance the TV and sound bar would automatically switch to the correct inputs, the volume control on the remote no matter which one you use in the chain of components should control the sound bar or receivers volume and not the TV and then turn off the devices you are not using. It is supposed to figure out what is connected and turned on and make smart decisions for inputs, which device to use for the volume, etc. In reality it is a cruel joke, and you swear your devices are possessed. Things turn on/off that you don't want. The volume sometimes controls the TV, sometimes the sound bar, and which input it picks is done by a roulette wheel. I had problems with equipment from the same manufacturer, like Sony TV, Blu-ray and Sound bar. So turn CEC off which will also turn off ARC.
To confuse things CEC is called different things by different manufacturers. For Sony it is called Bravia sync, Panasonic is Viera link, Samsung is Any-net, LG is simplink, etc.
So for your system connect all your devices to the sound bar. For instance
cable/satellite box > YSP 2200 w/ HDMI
Computer > YSP 2200 w/ HDMI
WD Live > YSP 2000 w/ HDMI
YSP 2200 > TV w/ HDMI
If you plan to use the TVs internal source such as an antenna or its Apps then:
TV > YSP 2200 w/ optical instead of using ARC/CEC via the HDMI.
Use your Harmony, you'll be happy you did. If you try to connect all the devices to the TV and try to use ARC for sound, CEC will wreck havoc with the harmony. It's as ugly as the republican and democrats fighting for who has control:-)