R – n equivalent to the SPWeb.Properties in the SharePoint web services

Here is some code http://geek.hubkey.com/2007/10/upload-file-to-sharepoint-document.html

As for why it is that is the way because Microsoft wrote it that way :). Some people have written custom web services that combine them, http://www.sharepointblogs.com/ssa/archive/2006/11/30/wsuploadservice-web-service-for-uploading-documents-into-sharepoint.aspx

Using the built in web services you have to upload the file and upload CAML which contains the columns. Another option if you are using a MS-Office document is to make sure the author fills in the properties in the document then you can have those fields displayed in sharepoint.

It's exceedingly (well, maybe not exceedingly) easy to create your own SharePoint-aware web service. If the existing API isn't sufficient to meet your needs, then you might consider rolling your own to give you more domain-specific functionality. I found this MSDN article to be pretty helpful, and I rolled up the WSDL modifications into a post-build event to simplify the edit-build-deploy process.

http://msdn.microsoft.com/en-us/library/ms464040.aspx