To answer your first question, this can be fairly straight forward depending on the data. We have a variety of Service-based applications that do exactly what you are asking. Typically, we parse the incoming file and wrap our own Postscript or PCL around it. If you layout is fairly simple, then there are some very basic PCL codes you can wrap it with to provide the font/print layup you want (I'd be more then happy to give you some guidance here offline).
One you have a print ready file you can send it to a UNC printer that is shared, directly to a locally installed printer, or even to the IP of the device (RAW or LPR type data).
If, however, you are going down the PDF path, the simplest method is to send the PDF output to a printer that supports direct PDF printing (many do now). In this case you just send the PDF to the device and away it prints.
The other option is to launch Ghostscript which should be free for your needs (check the licensing as they have a few different version, some GNU, some GPL etc.) and either use it's built in print function or simply convert to Postscript and send to the device. I've used Ghostscript many times in Service apps but not a huge fan as you will basically be shelling out and executing a command line app to do the conversion. That being said, it's a stable app that does tend to fail gracefully
