1. Yes, you can achieve that by modifiyng the RaceConfig.xml. You can also change ingame when setting up a custom race.
2+3. Booth can be achieved when creating a new map with the Map Editor (I assume you have Ultimate Edition or TotA). You can give yourself as many ships and planets as you want. You can even set up a whole galaxy with none of the planets not being colonized.
If you want to change the vanilla campaigns, look inside the Campaigns Folder and/or use the Campaign/Scenario Editor to change.
You could also use the map editor to change the vanilla maps to give you more planets and/or ships.