I2P on laptop: How to properly shut down the router?

I installed I2P on a Linux laptop. For the moment I'd prefer not to have I2P to start automatically as system service. The installation guide says that after installation I can simply run i2prouter start, which starts the service and opens the router console on my browser; I've configured the router.

Question 1: what's the best way to shut down router and service, when I need to? The guide above says I can use the command i2prouter stop; but I also see buttons on the browser console and on the tray on the taskbar.

Question 2: I've also noticed that sometimes after i2prouter start I get asked again to configure the router. How do I make sure the configuration is saved once and for all?

Unfortunately I didn't find anything about these specific points in guides or FAQs.

Thanks for helping!