Yes.

No, the mod has a lot of client code, so it would not be allowed on mod.io.

Yes. Copies of each GPS are created and managed so that each GPS looks like it moves in conjunction with whatever zone it was originally placed in (i.e. a GPS on your planetary base will look like it moves with the planet from space).

The copy GPS that is used as a proxy will have "PROXY_DO_NOT_EDIT" in its description. For the most part, you should not try to modify the proxy GPS since those changes will be overridden by the original. The only exception is the "Show on HUD" option which can used to show/hide both the original and the proxy.

They will work within a zone, but generally not between them. Transitioning between zones involves teleporting, so antenna visibility between zones is not guaranteed.

Solar panels and oxygen farms should work. The Custom Controller "Always aim at sun" option also appears to work. "Isy's Solar Alignment Script" also seems to work.

As with antennas, they will have issues when moving between zones because coordinates may not be what you expect (the true voxel planet positions are generally far away from their proxy counterparts). I will probably add hooks for programmable blocks later so that pathfinding scripts can be adapted for RSS use.

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Most likely a conflict with another mod that modifies GPSs. It may be possible to fix certain conflicts, so be sure to report any issues you find.

When transitioning between zones, the frame of reference changes, so grid velocity will change to match the new zone. Similarly, when transitioning between ORBIT and SURFACE zones, grids will teleport based on the current rotation of the planet. Both the teleports and sudden change in velocity may cause issues with subgrids in some cases.

If you are having stability issues with the teleports, you may want to try setting <EnableGridRotationOnZoneTransition> in the ConfigSettings.xml file to false. This will disable the rotation override when going between ORBIT and SURFACE zones (will introduce a visual discontinuity for grid rotation when transitioning, but makes subgrids much more stable).

To start, make sure that "Enable sun rotation" is checked in the world settings. The sunlight cannot rotate without this option on. Also, make sure there is at least one star in the world.

The sunlight direction in RSS (and RealStars) is dictated by the location of the nearest star(s), weighted by their apparent brightness. The sunlight direction is also bound by the sunlight axis of the world, so if you are too far above or below the plane that sunlight rotates in, the sunlight direction will look wrong. In general, you should avoid having planets orbit directly above/below the star if you want to avoid wonky lighting.

The sunlight axis is determined on world creation and can only be changed afterward by editing the save files. The RealStars mod page explains in more detail, but in general this is why you should never start with the vanilla "Empty World" when using this mod. The sunlight axis in that world is slanted by about 30 degrees by default.

If you want to create your own world from scratch, make sure to start with the vanilla "Star System" scenario, delete all of the existing planets, and then start building your system. The sunlight in the vanilla "Star System" is set to orbit around the Y-axis, so it lines up with the default orbital axis used in RSS.

When you get too far from the world origin (0,0,0), some aspects of the game may start to run into severe precision issues (MES grids spawning underground, spotlight block lights offset from the block, etc.). The solution is generally to try to not go beyond about 50,000 km from the origin. Since this would severely constrain gameplay and solar system design, what you can do instead is keep the terrestrial voxel planets close to the origin, but have the proxies be wherever they need to be. This will ensure that you at least have more precise/stable behavior while on the surface of planets where precision loss is most noticeable.

Steps (for new system):
1. Set "V-Planet Range Min" to 600000 and "V-Planet Range Max" to 1200000.
2. Spawn all stars.
3. Set "V-Planet Range Min" to 50000 and "V-Planet Range Max" to 80000.
4. Spawn all gas giants.
5. Set "V-Planet Range Min" to 0 and "V-Planet Range Max" to 50000.
6. Spawn all terrestrial planets.

Steps (for existing system):
NOTE: This will delete and recreate all planets.
1. Set "V-Planet Range Min" to 600000 and "V-Planet Range Max" to 1200000.
2. Select "Recreate Planet" under Hierarchy Options for each star.
3. Set "V-Planet Range Min" to 50000 and "V-Planet Range Max" to 80000.
4. Select "Recreate Planet" under Hierarchy Options for each gas giant.
5. Set "V-Planet Range Min" to 0 and "V-Planet Range Max" to 50000.
6. Select "Recreate Planet" under Hierarchy Options for each terrestrial planet.

You can adjust the ranges as needed if you are still running into precision issues or if gravity wells are overlapping each other. You can double-check the results of the respawning by toggling on "Mark True Bodies" to see where the real planets are positioned.

To any one that has been having issues getting economy to run on RSS worlds, you can follow the steps listed to fix a world so that the datapads will spawn into the respawn pods.

1. Open your Sandbox.sbc and delete the entire <Factions> block (the outer one!)
2. Find the line "<GenerateFactionsOnStart>false</GenerateFactionsOnStart>", and set it to "true".
3. Load back in and you should start seeing datapads spawn in respawn pods near planets.

Source: https://support.keenswh.com/spaceengineers/pc/topic/44358#comment-89042

Asteroids are, by default, set to not appear at all in proxy space (between planets). You can change this option by setting <DisableAsteroidsInProxySpace> in the Config.xml to false. You can also control which planets/stars have asteroids within their zones with the <AsteroidsEnabled> option for each body.

Generally, I would recommend leaving asteroids in proxy space off since they can make transitioning between zones look strange (you'll see them pop in/out when you teleport) and potentially cause odd issues if you build on an asteroid that is in the path of a planet.

I'll need to know exactly which mod is causing problems (and ideally which feature within it) before I can really address any performance issues. Try running on a world without any other mods to verify if the problem is a mod conflict. Also, try to isolate the mod causing problems by removing them one at a time.

Steps to Try:
1. Remove RSS from the world and leave all of the dependency mods (the world will still function, but the planets will be far apart)
2. If that doesn't work, try removing "Override Solar Blocks"
3. Then try removing "Visual Overrides API"
4. Try removing all rings from Gas Giants
5. Then try deleting all Gas Giants and then removing the RGG mod
6. Then try deleting all Stars and then removing the RS mod

If any of these steps alleviates the sim speed problem, let me know. Any additional information will help me potentially track down the issue.