1. Will comments and symbols be included in this upload (without offline source code)?
2. What physical interfaces are there to connect to the controller?
3. What is the procedure for an upload?
4. What about the firmware version? If the controller firmware version is not installed on my pc with RSLogix 5000, what then?
1. As per the post above, only v21 and later controllers store the comments onboard. Version 21 is relatively new, so if you don't have a copy of the program, it's likely to be an older version. So most likely no, you won't get comments. If the code is well written and tag names set up logically, you can generally get away without comments anyway. If, however, they've let an SLC programmer who's stuck in his ways get in there and create an array of 200 INT's called N7, well, you may find it harder.
2. We would need more information to give you a definitive answer on this one. But generally, a ControlLogix chassis will contain an ethernet card, which you will use to communicate with the processor via the backplane
3. Create your driver in RSLinx and set your computer's interface to the correct settings. Again, we will need more information to give you specifics, but if you have an ethernet connection, use the ethernet/ip devices driver and set your computer's ethernet port to an IP address on the same subnet as the ControlLogix chassis ethernet card (but not the same address!). Then in RSLogix 5000, click Communication>Who Active, select the driver you created, and drill down to the PLC via the interface card. Then click Upload. You may need to specify a file name and location to save the uploaded file.
4. As the post above mentioned, if you do not have the correct version of RSLogix5000 on your PC, then you cannot upload or go online with the PLC. This (generally*) is only relevant for the MAJOR revision: e.g. if the PLC has firmware version 17.11 and you have RSLogix version 17.00 then you can go online. But if the PLC firmware is version 16.xx and you don't have RSLogix version 16, you can't upload or go online. You will likely need to contact your RA distributor to obtain older versions of Logix5000. Some of the newer versions are available for download online if you have a support contract, but again, if nobody has a copy of the code, I would be guessing it's an older PLC.
Hope that helps, as I say, if you can give some more specific details we can possibly give some more specific answers, but hopefully that gets you started.
*Version 20 and 21 have issues between minor revisions. See these articles for more information:
http://www.theautomationblog.com/wh...fore-upgrading-to-rslogix-5000-version-20-03/
http://www.theautomationblog.com/what-you-need-to-know-about-studio-5000-version-22-23-and-24/