It seems that a few of the people who requested the beta did not receive it - in some cases because they were blocked from receiving zipped executable files.
Anyhow, I got some useful feedback, and am working on a version with three updated features.
1) The mouse scroll button now allows you to zoom.
2) The "black" model issue was, as suspected, caused by inverted normals (where the normal points "in" instead of "out". It seems the game does not care about those, but my DirectX code does. This problem has now been solved.
3) I am adding a "Save As..." feature to allow saving of retextured models.
I am also improving the documentation, so I should have the full (non-beta) version ready soon. but I am leaving on a small business trip tomorrow, so I will not be able to finish this until after I return next week.