J.C.MacSwell

Yes, up to but not including, 2c. (locally) (first question is no anyway due to Hubble but yes locally in either objects rest frame)

The simplest way to beat gravity is the "bootstrap" method. You need good balance and very strong arms and laces (regular shoe laces will probably break). You lean over so that your center of gravity is directly over your laces and pull straight up. If you pull hard enough (the force must exceed your weight plus the tension on your laces) you will rise and "hover" for a few seconds before falling over. Good balance is the key. Once you leave the ground it is like balancing a pencil on it's point so a couple of seconds is extremely good.

You are doing quite a job explaining Euclidean space. If you try real hard you can explain Euclidean space in a number of ways. You can come up with many more examples of Euclidean space. But it will still be Euclidean space. It will be a very good model of reality at low speeds and a very poor one when higher speeds are involved.

I think that if it was obvious we would already know what it was.

...and expand and/or contract, constantly or at a varying rate, with respect to another frame.

You will be telling us at your Nobel prize acceptance speech! (I do not know but I'm sure it's not Euclidean)

Johnny, this is how these frames work by definition. If you somehow come up with absolute frames that work differently that would be great. I won't say it is impossible. But, the way these frames are defined, that is the way they work.

When it is not an inertial frame the forces do not have to net to zero to have the particle/body remain stationary in that frame. It often requires a pseudo force (coriollis etc.) to accomplish this.

This is a very commonly used frame, perhaps the most common. Be careful not to use this frame in extremes however. The speed of light is not constant in this frame.

I think they meant if they were only 2D they would disappear to the others in 2D. Similarly if you are only 3D you would disappear into a fourth dimension.

Keep in mind the Universe cannot be defined as a frame in this sense. It includes all frames.

It's a Bi-ped for sure, as the sea turtle entering the bottom of the picture can clearly see! Obviously some humanoid arrived first, followed by even more intelligent sea creatures that do not require spacesuits in that atmosphere. As for the colour of the surface, I don't think we should jump to any conclusions without some more data.

Has temperature/emits photons.

I think you are right if your assumptions are right. However, I think you are not right, except when your "loop" is at rest (not spinning).

Blades/runners work much better but make sure the water is solid.

"Isentropic Red"

Yep, Lorentz and Galileo. Clearly there ain't enough room in this town for the two of them. Now, a kinder, gentler town (read lower the relative speeds of them yardsticks). I can see maybe they might get along a little better there. (not perfectly though)

LCF system:2 ends cannot coincide simultaneously Galilean: 2 ends can coincide simultaneously

This proves that, assuming LCF and your other assumptions are correct, that Galilean transformatons (especially at those speeds) are incorrect.

If you believed that back in Olber's time "they locked you up". Olber was a 19th century German astromomer. The expansion of space was not popularized until the 1920s.