No problem. Start will start your server when it is stopped. Launch just means that it will launch your actual game, through steam for example (Like a direct connect).
Due to the game limitations, seeds can not be changed currently, but you can create a new map by checking the box Delete World Save at the top right in your control panel, then restart at the bottom. (Green button)
If you are having account specific issues, please submit a support ticket and we will help you! The issues people are having are not all related and must be looked at individually.
Those settings will work great for you. Eco will save during the restarts. The validate update option is only needed if you are having issues with your server.
To answer your question, slots do not affect performance, unless of course you had more people on the server. If you are having any account specific issues, please submit a ticket!
Great question. We have a On the Horizon section on the footer of our website. We are aware of Rust coming to consoles and if it is a viable option, we will be looking into that as well!