What element is used for inserting a vector graphic logo. I have it in resources, but cannot access it/select it. What am I missing here? Just when I think I have it mostly figured out. Getting closer every day though.

Just guessing - but if it is in resources - say, for example, in a folder named images, it might not show in preview, if RSD doesn't recognize the file type as a graphic for the purpose of adding it as a local graphic, but if you put the relative URL in instead of saying local image (again, just a guess) ./images/myvector.svg it might work after you export.
<using a picture element as the container>

Browser should be accepting .svg files, just just any vector graphic. You would need to convert any vector you have to a .svg. RSD does not yet preview .svg files.