Answer:
Each LPAR sees only itself. On an LPAR that has release X - enter the authorization codes which is relevant to release X.
The result may be that more than one authorization code will be used in same box.
Answer: iSecurity GUI will run on any Windows edition starting (and including) Windows 98 (2nd Edition).
iSecurity GUI is a Java program and thus run on any platform supported by Sun. Please find the complete list here.