How do I design a 100 mm thick barrier that maximizes thermal and acoustic insulation?
For thermal, you'll want closed cell foam of some sort. If the wall has to be structural, I'd frame with vertical 2x4s, then on the interior, horizontal 1x1s, spray foam, then your metal panels. 

If it doesn't have to be structural, 4" of XPS foam board should work. 

That'd be about the best you could do for a thermal barrier. 

As for sound proofing, that's a bit of a different goal...especially with interior metal walls...which will reflect a lot of the sound. 4" of insulation and well sealed door openings should get you a decent level of sound deadening, but It definitely won't be sound proof by any means.