I also am trying to put wordpress on my DV base with media temple. Just signed up today. *BANGS HEAD ON WALL* Having problems with the exact same things so far.
chmod of .htaccess fixed that problem.
this is not a good solution but if you do the following command on your upload folder:
chmod 767 -R uploads
you will be able to use the uploads, however this makes it world writeable which is scary. I have not got the plugins to work yet. If anyone has any advice/fixes let me know as well.
