I just downloaded the Alpha Edition of Galactic Civilization III. Like what I see so far but I do have one request. Can the start up script be adjusted to require thick rings around Saturn and can the editable terrain on Earth be limited to land tiles? I would also ask that Greenland not be one of the tiles, not to knock Greenland as I'm sure it's a great place, but it should not take precedence over the main continents of the Americas, Europe, Africa, Asia, Australia or even Antarctica. Also, this is less important, can the users have the option on where the Capitol tile will be placed? I know these are small things but the accuracy in depicting the Sol system would be nice.
Welcome to the fan base. Have you perused some of the locations the tabs at the top of this screen takes you? There is much of interest about the plans they have for GC3 as it is being developed, and I think you will find some answers to your questions there, not as direct answers, but in what will give you a feel for where the game is now at Alpha 2 and where they plan to go.
For example, your questions are very specific and beyond the level of the game as it is now. Much of the code contains place holders and simple mechanisms that will be replaced as the game is developed. This includes more detail in the graphics, better alignment of build-able tiles to world surface, and much more. The last "dev stream" showed the improvements being made in placing buildable tiles on planets.
Your request for being able to place the Capitol tile yourself I think is a good one. I think it would be great if the devs could set up the colonization of a planet so that the first thing you must do is select a buildable tile for the colony's capital.