IANAL but my take is...
1 So, should I assume that porting an earlier version, of which I am the sole author is prefereable to porting a later version that has had input from other wikipedians?
Yes.
2 What if the later version had limited input from other wikipedians? Spelling and grammar corrections, or wikilinking? Am I right to assume this is sufficient input that I can no longer consider myself the sole author?
No, this is not right. There is something called de minimus--basically, when the contribution is so trivial it would never be entertained as a violation. Spelling and a minor grammar correction or two and wikilinking are perfect examples. The idea is, would a court entertain a suit brought by someone for copyright violation because he corrected a few misspelled words? No, it would be thrown out as trivial. This is de minimus and such suits are not entertained--if someone even went through the expense to try in the first place.
3 What if I use a later version,that had limited input from other wikipedians, but I excised all the paragraphs other wikipedians added, leaing only my own work?
That's I think the best option. We should try to avoid even de minimus stuff.
4 Someone wrote above that they learned, in high school, that paraphrasing was copying? For our purposes is this really correct?
When one is relying on a book or article as source, what else is there to do but paraphrase or quote? Copying close paraphrasing from a WP article would mean you'd need to attribute it as from them, however.
5 About GFDL, I thought that, since it requires giving credit to everyone who contributed, so that if we used material that had been liscenced to the wikipedia the wikipedia's edit history would have to be available for it to be used here. If that is true, wouldn't it represent a problem if an article here, based on a wikipedia, where the original wikipedia version was deleted? If it were deleted there would be no publicly available edit history. So, I am concernced we would no longer be honoring the original wikipedia contributors GFDL rights. Similarly, if the wikipedia version was renamed, this might be almost as bad as if it were deleted. 6 Does this imply we really ought to mirror the previous edit history of articles that were orginally from the wikipedia?
This is one reason why the GFDL is a monstrosity for an encyclopedia. It can't feasibly be followed. In practice, WP has acted like its contributors cede to WP the right to be attributed as an entity. So have its contributors for the most part.
7 I am sorry. I am new here, and I assumed that the limited number of contributions I have made here were under the GFDL. If that is not true under what liscense did I release that material, and are the rights I retain very different to the rights I retain under the GFDL?
We don't know which license yet. See
http://en.citizendium.org/wiki/CZ:License_EssaysI have read of some commercial sites that offer a wiki to their paying customers, that advertized a tool that would archive all the articles in a list of articles into a package that could dearchived on another wiki that used the same software. I dunno if that commercial site used Mediawiki. I dunno if the archive preserved the entire edit history.
Am I correct to assume we have nothing like that here? That there is no tool like this built in to Mediawiki?
As I wrote elsewhere a small but dedicated group on the wikipedia seems to have decided to remove a bunch of articles I am the primary author under "notability". I would love to be able to pack them all up, and unpack them somewhere more welcoming.
The only options I am aware of are getting all the data dump or importing one at a time. Oh, and there is also a java tool Veropedia is using to import from WP in a click or two, if I can read the java right, that is.