After filing a utility patent a simpler embodiment of the invention came to mind as a separate product. The simpler embodiment is covered in the first claim only since the dependent claims define the original preferred embodiment. The simpler embodiment requires a curtain shape (form) to function and is also ornamental. My questions is: Should I file a design patent on the simpler embodiment for it's individual protection, and should I use the title of the original utility patent or do I (or can I) make the title more descriptive of the simpler embodiment which is different? Also, the single design claim would be different.
Design patents cover the ornamental aspects of an object. If a shape has functional properties it can't be covered by a design patent. This is a complex area where judges try to separate the ornamental from the functional if you end up in court.
If the broadest claim in the utility application covers the new embodiment you might leave it at that. However you might be vulnerable to a court challenge one day based on lack of written description if you go after someone who uses the simpler approach.
You have a contradiction in your description of this "new" embodiment. An "ornamental" feature CANNOT be functional. It might be pretty, and it might be pretty in a really cool way, but if it is required to be shaped some way in order to function, it is not "ornament".
Let's suppose for a moment that you've created the (working!) Perpetual Motion Energy Machine and you discover that by creating a flywheel with a diameter equal to the length of the shaft, and painted with a Teflon-containing paint, that the device magically does stuff. That diameter isn't "ornamental", it's required for the device to function. Likewise, the Teflon paint isn't ornamental. But if you put some kind of "hypnotic spiral" in the paint ... so people don't realize the device doesn't work ... THAT is purely ornamental.
You have 2 questions. As usual, you should always seek out counsel for your particular case. No general answer here can replace real personalized counsel. That said, you can find a lot of information online that will answer these questions.
Should I file a design patent on the simpler embodiment for it's individual protection...
The answer of "Should I file a design patent" is entirely subjective based on your individual needs. Only you and counsel can answer this.
should I use the title of the original utility patent or do I (or can I) make the title more descriptive of the simpler embodiment which is different?
This is probably also subjective based on what you want to do. It won't affect the quality of the patent. The USPTO treats the applications as separate.
The Difference Between Design and Utility Patents
In general terms, a "utility patent" protects the way an article is used and works (35 U.S.C. 101), while a "design patent" protects the way an article looks (35 U.S.C. 171). Both design and utility patents may be obtained on an article if invention resides both in its utility and ornamental appearance. While utility and design patents afford legally separate protection, the utility and ornamentality of an article are not easily separable. Articles of manufacture may possess both functional and ornamental characteristics.
It looks like you can do both-- whether you should or not requires more Q&A you should probably discuss with counsel.