First of all, thank you for your interest in RadImageEditor.
Now, I'll go straight to your questions - the current implementation of the DrawTextTool doesn't provide a way to change the text's font family out-of-the-box. However, you could implement your own draw text tool with the corresponding settings and use it in the RadImageEditor. For more information about how to create a custom tool, you could check the Custom Watermark Tool
demo from our SDK repository on GitHub or the example here
from our online Silverlight demos.
About storing and retrieving images - RadImageEditor can load and save images in different file formats. This functionality is implemented through format providers. More about import/export functionality you could read in this help article
I hope this helps.
If you have further questions, I'll be glad to assist you.
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