The questions on donating to charity only relate to donating money to charity. Some people who have sufficient free time but little disposable income donate time to charities instead. I have seen reports that donating time over money is more common amongst students and people of low income, who seem to be a smaller proportion of the LW diaspora, but it may be interesting to compare donated time vs money on future surveys.
In my experience donating one's time is also seen as being extra keen on that cause, presumably because it requires more effort, and there are certain causes that consider time more valuable than funds (eg local environmental causes, where hiring sufficient people to remove invasive weeds from a local swamp is more expensive than holding a big weeding exercise on a Saturday afternoon).
When I was doing the survey I found the 'Highest Education Credential Earning' question difficult because the credentials listed don't match those in my home country, Australia. For example, we have a system of "technical certificates" that fall in between High School and Bachelor's degrees. (I think I chose '2 year degree' as the closest approximation, even though mine only took 1 year to complete.) And I know that doing a Bachelors in some areas is the functional equivalent of doing a Masters in others.
Would a question asking for how many years of post-schooling study one has completed be more or less useful? The wording could be tricky, since then there is ambiguity about whether to list time spent if one is part way through a qualification. If the majority of respondents are from places that match the listed options then mucking about with the question may not be of much value either.