[Brian]

Rogbar, we'll be adding iCloud support, but at the moment, to copy the data back to your server, you press the "Share" button underneath the document in the picker. (Leftmost button, box with a curved arrow on it.)

There's no specific number of rows or columns which will cause performance issues. Performance does relate to those factors, as well as your use of styles, the number and type of attachments....

If it helps at all, my most complex document has 14 columns, 5 named styles, and 809 rows. Works fine on my iPad 2. (No attachments, though.)