What determines a Kerbal’s uniform

According to their blog, the latest version of the demo is based off of 0.18.2. This means you have docking, which was added in .18. There are some restrictions from the full version, though:

• Part loading limited to the 25 stock ones.
• No Plugin loading.
• SPH and Runway Facilities are inaccessible.
• Only one save profile allowed.
• Cannot launch new flights if 3 or more are already in progress.
• Kerbin, the Mun and the Sun are the only celestial bodies in the solar system.

You should be able to see the version in the bottom right corner of the main screen, once the game has loaded. Currently, you're at least two versions behind.

If you want the science from experiments, you must either transmit it, or return the experiments to the surface of Kerbin. The experimental equipment itself doesn't actually have to make it back to Kerbin though; A kerbonaut can retrieve the data and store it in a command pod that's headed back to Kerbin. There are some restrictions to this, though: you can't store multiple copies of the same experiment/biome/altitude combination, and I haven't seen a way of removing research data from a mobile lab. As a side note, you can store multiple crew reports by performing an EVA, taking the data from the command module, and then returning to the module.

Your experiments also don't have to be attached to the capsule when you return ‒ you can recover experiments returned as debris by disconnecting a science stage from a capsule; however this may be impractical due to limitations of the game where after a certain threshold, debris (or even whole aircraft/spacecraft) will be unloaded when in atmosphere, but it does mean that you don't need to perform an EVA to retrieve the data.

Some science experiments also have a transmission cap where as little as 25% of the data can be transmitted back to Kerbin; eventually, experiments must be returned to max out available science. However, when return is non-trivial, taking the hit in transmission might be worth it (for instance, if the target is the surface of Tylo or Eve). Take a look at the science wiki page for more information.