Two points, you probably want to reduce the pseudo-niters-min, you don’t want to force the system to take 100 steps if it has already converged, 4 is probably more appropriate. For pseudo-niters-max, 100 is probably better too.
PyFR doesn’t assume units, see one of the many other posts asking similar questions.
For example:
Finally on you question about GMSH, this might be better asked to there support team/community.