Much of this discussions seems like miscommunication, or perhaps mis-understood expectations. However leaving that, and to your original question.

Can you protect yourself and your work/credit?

TL;DR: no. Not in a practical sense.

When you create work, you copyright it. I think we all get that. However proving copyright, in a legal sense, and wanting to prove it, in a practical sense, are different things.

The proving piece: You could drop a copy with a lawyer, expensive, and frankly, not worth it. Personally, if I had any item that I was concerned about in a technical sense, I'd post a draft blog, or email to a gmail/hotmail/etc. address that would establish some timestamp. That's probably good enough evidence in small claims court, and make no mistake, we're talking small claims here. If it were a larger issue, as a screen play that Grant mentioned, I'd seriously consider contacting a lawyer as an independent escrow place as well as something like the Screen Actor's Guild.

In a practical sense, there's not much to be done. You send me something as an editor, I decide to take credit, what can you do? I publish it. You can rail about it online, but that may or may not work. It might get the editor fired, which is turnabout/fair play, but it may not get you credit. There could be an argument, as the editor could "re-word" your piece and use their name. Ultimately it isn't worth suing about for a technical piece from your perspective, and while you might even get paid, I'm not sure you'd get credit. Even if you did, it's not likely worth it. You would get the byline, but you might never want to write again if that's the hassle.

However in a more practical sense, it doesn't really happen. First, your ideas aren't great. I'll say that almost nothing I see published in the technical area is worthy of protection as an idea. In terms of the work to get the actual words down, sure, but the ideas aren't. We get submissions all the time, and you might be surprised how often I get similar submissions in the same month/quarter. This isn't a "stealing" of ideas, and it's usually not a stealing of work. Most of the copyright seems to be lower-fruit. People take what you've published on a blog or site like SQLServerCentral and republish it themselves to boost their audience.

Editors need writers. We can't do it ourselves, and if we use their content without paying or credit (which is more important from what I've seen in over a decade), we lose the authors. Which means more work for us to find more content/authors.

It just doesn't happen as you've theorized.

What I do/did before I had this job. Write, submit to an editor, keep track, and ask for copyright retention. Give them 30/60/180/360 days exclusive publication right and perpetual rights, but retain copyright. Not everyone allows this, but you decide then if you want them to publish. Some will anyway and pay you and claim a mistake, but then you can move on to somewhere else as a publisher.

From my perspective, I'd be happy to view pieces and give feedback. We publish and don't take copyright. We don't care if you are exclusive or if you want to write for every other place.

HTH