How much of this advice is generally applicable outside the US?

Many of the questions ask you to pick among 'Strongly disagree' through 'Strongly agree' and most questions are optional. For those likert/select-an-option questions, I guess the survey analysers would do more aggregation among survey-takers, so quantity would matter there.

For context, Kirsten has long worked for UK government departments.

No. It just has a question ‘Where are you based in the UK?’, with an option to say ‘not UK-based’ and specify where you are.

Grayden comments:

I think generally they are looking for issues to consider rather than doing a straw poll of public opinion, hence quality over quantity

Yes; that Google doc is linked to as the call to action of the linked post :)

Emile is often the source for articles on EA in the media. (link to duplicate comment in other subthread, with examples)