Use Google Takeout. You can choose which formats you want for your exported files by clicking in the "Configure..." area and selecting the appropriate formats from the drop-down lists.
Alternatively, you can either use the "Export" menu item when editing an individual document, or you can also download the documents from your Google Drive homepage.
Select one or more files and then click on "Export" from the "More Actions" menu. Next, pick the format (e.g. PDF, Microsoft Word, etc) you want for your exported files. Finally, click "Continue" and we'll give you a zip file to download that has all your content.
Conversions to and from new formats are being added at regular intervals. The last major update to the list of possible conversion types is outlined in this blog post.
There's also a help article on manually downloading your content from Drive and the formats that are currently supported.
Escaping to Google Drive
Moving your documents, presentations, and spreadsheets into Google Drive can be done by various methods. The fastest would be to install Google Drive for your desktop (instructions here). Then you can just drop your files into the folder created on your desktop and they will be made available on the drive.google.com site.
You can also upload the files or folders directly in the website. Just click on the upload button (to the right of the "Create" button). On Chrome you can choose to upload either files or folders; on other browsers an applet will need to be installed to upload folders. You can find more details in this help article.