I am confused about just what plants you have and what symptoms they are each exhibiting. A photo of each plant that shows the entire plant, including its pot, would be more helpful than single leaf photos.
There are a variety of Yuccas and there is a Yucca elephantipes, but not a Yucca elephantipes. Palm is a very broad category of plants with hundreds of species.
I have no experience with Mexican Cucumber, but I doubt that they would fare well indoors even just in winter.
There are much easier and simpler safe and effective treatments for indoor plant pests than what Rodale's is suggesting.
