Once DNS has updated and you can reach your site by browsing to it, just use yourdomain.tld as your ftp server.
Not likely (either nero.dreamhost.com or yourdomain.tld should work). It is likely that they are actually being uploaded, but have gone into the wrong directory. Try looking at your space with a real FTP client instead of DreamWeaver, so you can better see and understand the directory structure.
In a pinch, you can also just use the [/url=http://wiki.dreamhost.com/FTP#DreamHost_WebFTP_Support]DreamHost WebFTP program[/url] to look around (though I do not recommend using it for any serious work)