Your skin will tell you when it's had enough. If you notice persistent redness, new breakouts, stinging or burning sensations, or flaky patches, your skin barrier is sending you a clear message.
If your devices only support up to 4K at 60Hz, a "premium high-speed" HDMI cable (18Gbps, HDMI 2.0) is perfectly fine. Again, just avoid really old or thin cables. Early HDMI cables (HDMI 1.4 or older ...