Downloading the original pictures uploaded to Picasa all at once is easy if you're using Firefox. DownloadThemAll is a plug-in for Firefox which can be used for many things but I have found it most useful for me when needing access to original pictures from Picasa.
1) Download the plug-in DownloadThemAll and install it to your Firefox browser.
2) Go to the Picasa album where you want to download the pictures from
3) Picasa provides the RSS feed for the pictures so all you have to do is click on RSS on the right hand side of that page to bring up the feed.
4) Still with me? Now just right click on the screen and click on DownloadThemAll.
4-a) Save the files in a directory you specify and select Images under the filters.
5) PRESS START
One thing I am still trying to figure out with Picasa is how to display a random image from the album using the RSS feed... Any suggestions?