Still traveling, so no ULF calc update yet. Likely in the next few days.
Regarding the scaling...agree with the X axis and Y axis precision that have been mentioned. Definitely 5db for y axis.
Now for smoothing...IMO, it depends what you're trying to do.
I typically use no smoothing to ensure that I'm not hiding any peaks or nulls. Once I've dialed the response in so that I'm confident that those don't exist, I'll eq at the 1/6 scale. Once that is to my liking, I'll then flip to unsmoothed to ensure there are still no peaks or nulls I created in the process. Assuming I'm good there, I'll post my final curve at 1/6 smoothing.
Ultimately (from what I've gathered on this forum),1/6 smoothing is what we hear. If that's the case, then I want my final frequency response graph to show that.
However, if you're posting your response because you want assistance with your FR, or are comparing subwoofers, further precision is beneficial to really help reveal any potential issues. The minimum however for any posting of a response would be 1/6 scaling.