Oracle Database Discussions

We are experiencing a problem that many different users seem to have many different versions of tnsnames.ora. We want to create our "gold" version and ensure that everyone uses the same one. Two questions:

1. Is the "alias" that you give each connection case sensitive? For instance if I name one connection Prod is that the same as PROD?

2. At another place I worked I was under the impression that most applications (PL/SQL Developer for sure) uses the Windows PATH environment variable to locate tnsnames.ora by going through all directories listed in the variable and using the first occurrence of tnsnames.ora that it found. Through a little testing and renaming and such I have found that this doesn't appear to be the case. We are using ADI, Discoverer, different development tools, etc and would like to avoid having more than one location where the file is stored. What is the best way around that or is there a way? I assume that it depends somewhat on each application.

Thanks in advance for the help!