I've studied this issue for over 9 years and have a legal background... My impression is the following, regarding some of your questions:

The KJV is most definitely in the public domain, which makes it different from all of the progeny of the Revised English Version that have followed it. The KJV is only copyrighted when there are study notes, cross-references, maps and appendices added to it by some publishing houses. Those additions are what makes a copyright for any particular publishing of the KJV necessary.

Other versions, such as the NKJV, the NIV, the NASB, the ESV, etc., always have changes to the text itself that are sufficient to allow them to obtain a copyright, and thus to earn royalties. Compare, for example, the rendering of just these two verses: 2 Corinthians 2:17, and Genesis 15:1 in both the KJV and some other versions. Those are exemplary of the types of changes that are sufficient to consider them "different works" - and entitle them to avoid the "public domain" status of the KJV.

The answer to your fourth question would probably be yes, but I'm not an expert in copyright law. That's a big caveat. BTW, I believe that it's still the case that you need to make appropriate, precise attribution to a source from which you've taken something only IF you are going to make money for yourself or for the congregation from the sale of the materials you're distributing.

Any legal experts in intellectual property or copyright law out there? (I've done work in each that is pretty de minimis...) I will stand corrected if anything I've said is in error, and what I've stated here is not meant to be construed as legal advice.

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Margaret
Free Church of Scotland [Continuing]
Michigan

"He must increase, but I must decrease." - John 3:30