Unfortunately I have no idea what is causing either of these, based on the information given. It's certainly not an error I'm aware of on any other installations and I would suspect limitations by your PHP server. There is a small possibility that some of the changes in Moodle 1.0.1 may have fixed your first error (on uploaded files).
I've written to you via email for more details.
Installing and upgrading help
Error with uploading images and graphics and files
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