For the validations you can apply additional validations with the tool by editing the existing server validations that are on the page. You will find the existing validations in the server behaviors tab.
The image upload part can be handled with DFP, you would need to apply it once for each of the upload fields you would like to have in your form. You should be storing the name of the image file in the db. As for duplicate names DFP already accounts for this and will rename the new file or allow you to rename the old one.
After DFP is on the page you can use the bindings from these server behaviors for the server file name to insert into the record.