Importing XML is usually straightforward in Mendix. You can follow the steps here: Import XML Documents As long as the XML is valid, rich text attributes should import into Mendix.
Regarding the PDF attachments, how are those formatted? How are they associated to the XML data? A few more details would be helpful in providing you with some ideas about how to import those.
You can load the xml element into an entity string attribute and then use java action Base64DecodeToFile from community commons. In my experience, this can be a slow process if your files are large.
I am using above micro flow for saving the file but the file is saving twice. Is this is the correct way to save the file.
Created Variable with Base64 encoded string ,
created FileDocument object and using variable as encoded value and NewDocuments object as target file in java action.