You can check the structure of RadDocument here. The RadRichTextBox control has Document property which can be manipulated. Here is an article about ImageInline element. Note that images in the model of RadDocument do not have an analog of the ALT attribute, so this property will be stripped when you import an HTML document.
You can also check the related document element articles for the other properties you have in mind.
Do not hesitate to contact us if you have other questions.
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