As for H-1B "skilled workers"...that is a misnomer. The better term would be "credentialed workers." Credentials do NOT equal skill or suitability to a task. I've been involved in IT hiring for a decade. All H-1B workers without exception have impressive credentials, but most of them have next to no actual experience, and some are flatly unable to do the very tasks they are credentialed for. But they work for a fraction of the wage expected by skilled US workers, and-most insidiously-one rejects them at peril of being labelled a racist. There are a lot of hiring games being played, and quality suffers for it.
The last one is even equally problematic. The author argues, incorrectly, that salaries prove the absence of shortage. But he has not learned his economics properly. Price is indicative only when there is no rationing. Shortage of skill work is rationing. One cannot use the non-rationing tools (price) in situations where rationing exists; this is simply absurd. And yet, that is what the unsuspecting author does.
One of blogs/articles you have kindly made available does inadvertently argue against itself. It sites the fact that more than one half of the science/engineering students are foreign. Right here you can see that graduation data, sites by many opponents, do not apply. "See," they argue, "the number of engineering graduates increased from 72,000 to 81,000 in 1999-2004 -- we don't have any shortages thus." But one half of those graduates do not satisfy the citizenship requirement; we have therefore only 35,000-40,000 of American engineering graduates. Different picture, isn't it? Now the foreign students still apply for jobs, and some get it --- under H1B or some such visa. But now the opponents are railing against those. None of it makes sense. The arguments are supposedly common-sense level (who can argue with prices, for instance?) but are actually fallacious.
Finally, H1B visas cover not only electrical engineers and software specialists. Go to any major university and count the number of Americans in the graduate programs in science, engineering, or business. Count the faculty that teaches in the corresponding departments. I could name for you universities in which there is not a single American-born person in the entire area of teaching/research. Why this is happening can be discussed. But to deny the facts is unproductive.