Hello Thomas,
your first issue is a bit complex. The report page size in DIAdem is not specifically set in physical units (mm, inch, ...), but is defined only though an height-to-width ratio. This is intentional, as all graphics and texts placed on the report page are internally represented as vectors, thus providing the best possible display on all printouts. So when using A4, A5 or A3 paper, the print will always be sharp. If you desire to print e.g. on letter format pages, just enter the corresponding format name, ratio or page size in the master layout settings.
As you have noted correctly, the PDF Export function is in fact pre-set to A4 printing and cannot be changed. You can use the DIAdem PDF Printer accessible through the File»Print... dialog to set the desired paper size manually.
The second question of yours is more easy to answer: There is no TeX-like greek symbol notation in DIAdem available. So you can either use the "symbol" font from windows to display text in greek characters ("a" will be alpha, "b" will be beta, ...), but unfortunately, you cannot mix fonts in one text field, so an axis label would be completely typed in greek letters.
But... DIAdem supports unicode characters. Therefore, I recommend to use Microsoft's "CHARMAP.EXE" to get the sigma character σ (Unicode U3C3), copy it to the clipboard and simply insert it into the regular text like any other character in DIAdem. When using a unicode-enabled ttf font like Arial, the character will be displayed correctly in your axis labels.
Best regards,
Sebastian
