Well, you're still asking the wrong question (and getting the wrong responses)
See my answer to your first question, but here's a further clarification.
There is no such thing as an FTP file. FTP is a process, so I guess any file on your system is an FTP file because they all could have been placed on your system with the FTP protocol.
Source files are the files used to create your programs. Web pages don't have separate source files. The page is its own source file. (In any browser, use the 'view source' command to verify this.)
All of the files needed for your web page will be on your server. What you need to have from your developer is the full access to your server - the user name and password used to get onto your account through FTP and other means.
When you have this, you have everything you need.
When I take over a site for a client, if I can get access to the original site, I can get everything I need from it. However, if the site was that great, they didn't need me. Normally when I'm redoing a web site, there's very little I need from the original except perhaps some copy (which can be gotten with an ordinary web browser) and the domain name access (which requires an entirely different process.)
Get the username and password to your site, and keep them in a safe place. That's all you'll really need. If you have these, you have the source files, because they're on your server.
If it's a more complex site, (say a data-driven content management system or something) then you have a right o the code (which will be on your server) and decent documentation, including the names, usernames, and passwords of any databases used, and a list of the source files (which you'll already have.) You might also ask for documentation of any custom databases, as a second developer may find these very helpful (especially entity / relationship diagrams) These are more advanced features that most web sites don't have.
It sounds like you don't trust your developer. Maybe you should get a different one.