With regard to wordclock, what is important is setting up your devices correctly. As andyoc pointed out, you need to determine which device you want to be the source of your set-up’s wordclock – a.k.a. the “master” – and then setting all the others to slave (sometimes called “external”). The master device should be whichever one is most likely to output the best wordclock signal – usually the most expensive piece of gear. For most of us, who have an audio interface feeding a DAW, the wordclock signal is going through the same cable the digital audio signal is. Some devices have a dedicated BNC-type wordclock output/input to ensure even better integrity of the wordclock signal (since it doesn’t have to share the same cable with other signals). As Andy said, you can record with a setup where the wordclock isn’t set up correctly, but you’ll almost invariably have pop & click issues.*
*I’ve actually recorded whole songs without issue only to realize later I had both my A/D and Cubase set to Master