No, the length of the tube might slow the wind down, but it should still move air through the tube. I assume you are thinking of crawling through the tube. I would certainly take precautions before attempting such a thing. Perhaps search for spelunking resources that can tell you what equipment to take, what procedures to follow, etc.

It probably doesn't matter that much because the 1x6 should be attached to a 2x4 above it. Note that the 1x6 is only 3/4" thick, so it's a somewhat smaller target than you might think. You will want to use a pretty thick screw eye, especially if you are mounting it horizontally.

In general, you have to be the best of the best at something or the best at a bunch of somethings. Most astronauts start as test pilots or scientists. Almost all have advanced degrees in a relevant field.

I'm sure the path to astronaut will change a bit as many of the future astronauts will be flying for private companies, rather than for NASA, but one thing won't change. It will continue to be very expensive to launch a mission, and there will be a ton of people who would love to go, so the competition for the job will continue to be fierce.

Good luck!

Also remember that the $30K will probably qualify as income, so plan to save at least some of it for income tax. Of course this may not apply, depending on where you live.

I dislike the term "planetary embryo" because it implies that the body is destined to accumulate additional material and "grow up" to be a rocky planet (or something larger). That's only one of several possibilities.