Hi Bob,
Sorry, this post seemed to slip through the cracks. A few new releases to mojoPortal have been made since your post so items 1 and 2 may have been solved already. I do not experience these problems with the File Browser.
As for the 3rd item, this can be remedied by copy the AllowedUploadFileExtensions key in the web.config to the user.config and then adding .pps to the list. After saving the user.config, go back to the web.config and add a blank space to it at the bottom and save it (this causes the website app pool to recycle and reload the web.config and user.config).
Joe A, the AllowedUploadFileExtensions key in the web.config has a space in .mpeg (it is currently ".mp eg"). Also, do you think you can add .pps to the list?
HTH,
Joe D.