Newbie questions: installing i5/OS V5R4M0 on a 9406-800; re-using installed license keys.

Hi All,

forgive my newbie questions, but i need some extra info about some basic matters before i make a wrong decision.

Recently a company donated their old 9406-800 to me, which gave me the opportunity to FINALLY play around a bit with i5OS :)
The machine has a running copy of V5R4M5, with license keys. Passwords for QSECOFR and DST are written down.

I was able to borrow a copy of the V5R4M0 CD media, so i could perform a
clean reinstall (which will be a learning experience by itself :)
The machine has an onboard tapedrive, so i plan to perform a system backup before i touch anything else on the machine.

Some questions:


* what command is best to show me the installed license keys info, so
that i can write down the neccessary key strings and re-apply them while
performing a clean install?

* The installed OS is in Dutch, can i use the same license keys for the English version?
* The machine is running LIC V5R4M5. are their problems to be expected if i install LIC V5R4M0 from the CDs over the old LIC (basically
downgrading the LIC code?)
Thanks for any info...i've digged through several PDFs and forums, but
the licensing stuff still remains a bit of a mystery to me.

Regards,

Rene.