Hi,
Thank you for your interest in our viewer.
1) Translations are created by community and are available here:
http://www.radiantviewer.com/translation.php
2) autorun.inf automatically runs either 64-bit or 32-bit version depending on operating system version. If autorun is disabled, run.bat will always run 32-bit version. you could create run64.bat file that runs 64-bit version but auto detection is not possible in bat file.
3) splash screen cannot be disabled (the end-user must accept license terms due to legal reasons).
4) command line parameters are available only for installation version of RadiAnt:
http://www.radiantviewer.com/manual.php (at the bottom).
Kind regards,
Maciej