Re the OP’s issue with email passwords: I suspect the problem has self corrected at this point. When you add an email account in the panel, the change destined for a mail server is not made instantly. The success message in the panel will actually tell you the change you made will be working in 10-15 minutes. Sometimes tho it takes longer, I have no idea how to guess when the change has actually been pushed out from the panel to the server in question. There have been certain peak events (massive forced password change) in the past where the queue has backed up hours. Generally tho it may run a little longer than the expectation the panel itself sets.
Re, the missing URL: We do need more information here. Things that come to mind right off: is it the correct URL, I don’t use joomla but sometimes when a webapp is installed the first time loging comes from a one-time use setup URL. Another is, have any changes been made to the site via the dreamhost panel that would change DNS? The one I can think of right off is turning cloudflare on or off. If something is changed that changes the IP of the website it’s very possible for the site to disappear up to 72 hours (usually its under 4 hours, but could last longer).