1. In the research tab, you can check the tech tree that contains the various ship improvements tech-by-tech. Transports are first available with the "Planet Invasion" tech, which most people get around the start of the mid-game.
2. With various tech options, you should be able to boost economy, research, build legions, and so on without consuming a tile.
3. Alongside simply asking those questions here in the forums or searching the forums directly, you can also access the journal-section of the site and Ctrl+F your questions into the search bar. https://www.galciv3.com/journals