One thing with postdocs is that you have to be prepared to do something totally different (obviously same discipline!) from your PhD. If you did your PhD in a topic of your choosing, this is a big change.

It depends on what type of ethnographic study you're intending to do. Essentially ethnographic research is about observing the community, so whatever data you can gather is fine. It might be diaries if you're an embedded researcher, it can also be data gathered from artefacts and documents.

Has anyone had any experience with senior academics on panels for journals, workshops, or conferences stealing ideas from papers (accepted or rejected) for their own publications

I'm pretty sure that the one person can't decide on the job. It wasn't the case for me even though I was the only person interviewed (presumably I was the only person who matched the person specification). I'm a bit cynical - lots of internal university politics and procedures that mean you can't be sure that this is going to happen.

People encouraging you to apply certainly is no guarantee that you'll get the job in my experience - in fact it would be pretty worrying if it was!

I made some minor corrections (that I brought up at the end of the via IIRC) that they hadn't spotted. I also didn't make all the changes suggested as some didn't make sense, but I explained why.

Yes, definitely look up the work of your examiners.

I think for many PhD students (certainly at smaller institutions) establishing a network outside the university is vital! Going to a conference you'll meet other people doing similar work, so really make the most of it and give out cards if you have any.

I echo the comment above, good to see your supervisors so involved.

It can take a while to find suitable and willing examiners - you say some were contacted but they declined, so you know it's not straightforward. It took me a while to get suitable examiners too. They need to be an appropriate combination of experience and expertise.

The original post did not make it at all clear that you weren't talking about your doctoral research. What you decide on subsidiary projects is entirely between you and that person really. I wouldn't advise doing projects outside the PhD unless they do not get in the way of your "day job" and will result in a good quality paper.
As for the notion you need a particular status of person on the paper to get it published, personally I think that's codswallop. It would also be very dubious ethics on the part of this academic.

What is the problem with selecting the examiners? Have you made any suggestions about suitable examiners - that may resolve the impasse? Has your supervisor contacted anyone yet?

Personally I think such disclaimers are a bad idea. The literature review should be comprehensive - full stop.

You can gain a PhD by publication, when the entire PhD thesis is a collection of articles already published.

Personally I'd say the main issue is consent for the analysis here, since there was explicit consent (although not written) to the taking of the blood sample. It's certainly not good practice, but it shouldn't be fatal.