Thank you for your interest in RAOB. To answer your first question -- RAOB can be used anywhere, even on Mars. In fact RAOB does not care who or where it is being used. It only cares what format the sounding data comes in. And if RAOB can not decode the sounding data given it, you can manually enter the data and process any sounding data. You can even transform any sounding data into RAOB's CSV format for automated input.
Your references to the 5 configurations (such as Student, Forecaster, etc) are only pre-packaged RAOB bundles which offer cost discounts if purchased as such. You don't have to buy any of these bundles. In fact most users purchase individual program modules, or just initially purchase the Basic program, and then add optional modules later. In fact, you can purchase the RAOB Lite program for only $50 and still plot soundings anywhere in the world -- depending on the format of the sounding data being used.
Now to answer your specific questions ...
1) The difference between the Forecaster and Operational packages are evident in the optional program modules listed in the package columns. Just click on each module listed in the package column to see the available functions for each module. As indicated above, you can also purchase individual program modules here ... http://raob.com/order_form.php
2) RAOB can create cross-sections or time-sections between 2 to 2,000 sounding stations at a time, and plot them in a variety of diagram formats.
3) Dates and positions of sounding data are important when creating sectionals, but RAOB does not prevent you form creating diagrams. Soundings can be 3 seconds apart or 3 years apart -- it doesn't matter -- RAOB will create the diagram anyway. Just send me some sounding data and I will show you the diagrams that can be created by RAOB.
Please let me know if you have any other questions.