Well Is your server allowing you to delete the images from the uploads after they are moved to the data directory. I beleive this is your issue. If set to 777 basically that error is telling you that we have processed the file and deleting the upload one. Its not letting the script delete the file.
In line 87 of image-inc.php you can find the unlink statements and change the instance to @unlink and that will surpress an error.
You can then investigate with your host why your not being allowed to delete a file when the directory is 777 as it should be
On the daily upload issue just set in usergroup settings the max daily uploads you want. seems to me the user is uploading more files that you allow
