No Im afraid not!
Have you played any Half Life 1 mods? Basically the site of the mod will offer download links to a zipped or rar'd file. You then install these into the Red Orchestra directory within your Steam folder.
The installation process will dump a launch icon on your desktop where you launch that particular mod only. So if you feel like playing DH, you double click the relevant icon. Same with CC & MN!
In an ideal world, everything would be managed through your RO server browser or you will receive auto updates like games purchased through Steam. But sadly that will not be the case!
Someone correct me if Im wrong!