Knowing that the work involved could take days or even weeks of our limited spare time we needed to keep the original wordpress site up. We thought it reasonable to clone the old site and use a temporary domain while changes were made, then simply replace the old site with the changed assets and database.
So I needed to copy the old site's assets and media to a new web space on the host, and set up a copy of the database. Copying files between folders isn't an option within the host's control panel, so it was necessary to download everything via FTP, then re-upload it all to the new webspace.
Who'd have thought a 4 year old blog could accumulate over 9000 files taking up nearly 4Gb!?
Before uploading 4Gb of files I needed to upgrade our hosted file system limit, and even though this is a temporary measure our it means upgrading the annual contract.
Who'd have thought Wordpress embeds the full url for every internal link and media resource, so a page in the work-in-progress site was filled with links to the old site's assets, and clicking any link took us away from the work-in-progress to the old site.
Who'd have thought FTP would lose file permissions? All of the uploaded files were read-only, so any attempt at an edit through Wordpress's admin fetaures was rejected with an obscure error message. Getting this corrected needed intervention from the host's tech support because the control panel doesn't offer chmod and even thogh my FTP client tries the server didn't understand chmod.
Even then, who'd have thought you'd need to set everything to be writable by anonymous users under IIS. It's not enough to give the pplication pool account write permission. Wordpress under PHP on IIS operates as an anonymous user, so all files need to be wide open to all.