Hi VivaSuzi and thanks for the qRules questions!
We haven't tested this with the browser-enabled forms. One of the challenges with browser-enabling is that forms with code (and qRules is a code module that you inject in your form) require admin deploy. It's slightly more complicated, but not hard. Microsoft is making this simpler in the next release of SharePoint.
Uploading multiple file *attachments* or uploading multiple XML files? The former is supported. See: http://www.infopathdev.com/files/folders/qrules/entry40104.aspx. For the latter, we do have tools that support uploading multiple XML files to SharePoint via our DBXL SharePoint/SQL accelerator product. We call this tool Doc Deployer or Document Migration Tool. There should be some posts on it in the forum. You can use the new Google search for InfoPathDev to find stuff more easily: http://www.google.com/cse?cx=003654972516704994317%3A4j0mji2l1rq&ie=UTF-8&q=Document+Deployer+Migration+Tool&sa=Search
Deleting attachments could be done if they are just an XML node in a repeating section. But, I thought attachments weren't supported for browser-enabled forms. Once again, I think the story gets better in the next release, but that's "out there". If you are using the image attachment commands to upload from a rich client form, you could definitely delete these, but the images will still persist on SharePoint. We could add separate functionality to delete the images from SharePoint as well.
Saving a contract # for the uploaded file attachments can be done but woudl require some custom coding. qRules doesn't support that scenario out-of-the-box. Custom coding is slightly more difficult with qRules because it is a code module itself. With DBXL, you can save the separate file attachments or images as XML containers and you could easily extend those to have the contract # as a promoted property. With just stock file attachments and images, you would have to write code to set a custom column. Not hard, but probably an hour or two of consulting work.
We will add a feature case to our database for the testing in browser-enabled forms. Aside from that, the other stuff isn't too complicated but you may need a little programming help. We would be happy to assist you with your custom programming needs, or continue answering questions in the forum.
Best,