That’s a pretty old version. Please upgrade to v2.6.2.
That command is only meant to be used for quick local development. You shouldn’t use it in production.
You’ll need to elaborate. I’m not sure I understand your goal here. Just saying “zero downtime” is not clear enough.
Then why not use that Caddy to proxy whatever?
Do not remove any parts of the help topic template. It’s there for a reason. It’s a forum rule to completely fill it out. We need as much information as possible about your setup and what you’re trying to achieve to be able to help.