[off topic] looking for as/400 advice

Hello list,

We are looking for someone with experience on the as/400 (running
os/400) platform, particularly in legacy environments.  We are porting
an application to as many architectures as possible.  We know very
little about as/400, but we have had some customers request support.
Does anybody know the answers to the following questions?

*) is it possible to compile C with gcc (superficial search seems to
indicate no)?
*) if so, with what versions?
*) newer versions seem to run aix binaries.  Could a ported aix binary
read files off the os/400 filesystem and do something with them (ftp
for example) for backup purposes?
*) newer versions seem to have virtual machine technology...
*) other than built-in tape backup, does anybody have experience with
3rd party backup agents?
*) in modern terms, is aix and/or windows commonly deployed on top of os/400?

We have a acquired a number of legacy and (used) enterprise platforms
to compile on.   Of course, we will subscribe the more interesting
architectures to the buildfarm.

off-list response is of course preferred.  If you can answer our
questions but get paid for your time, feel free to respond.
Basically, we are looking for a os/400 expert who is familiar with
porting applications to the platform, including older versions.

merlin