4:2:0 can be forced due to dumb hardware. We have no choice. 4:2:2 is mostly for archival, not really distribution.
Trellis is mostly about efficiency in encoding, at a trade-off for time of encoding. When offline encoding, for offline viewing, this doesn't really matter. But for online viewing (non-Youtube/etc), or even just online transfer, it's better. Playback/decoding doesn't have the same complexity issue, unless you get crazy with other settings (causing severe bottlenecks, or even outright playback failure).
Adjusting max GOP to fps is probably fine. GOP isn't a fixed value with scene change detections turned on, so this may not have much actual effect. Longer GOP can increase efficiency of encoding, but it can also lead to "breathing" of the encode decay.
^ I've not had the need (or time) to delve into Hybrid much lately. I just use my presets for projects. Because of that, I may have forgotten some facts, or become overly outdated. So I asked Gemini to review my comments. Nope, I'm accurate! See attached.
BTW, I'm in the middle of creating my masterpiece AIW capture + encode/restore system, and plan to revisit the latest version of Hybrid in January. My current settings are based on the last Win7 version.