I am sorry but I cannot replicate your problems.
MacOSX 10.6.8 (ie not "wondows 7")
The print engine in FM has long been complained about by every FM Developer I have ever known. Unfortunately I don't see any of these things being fixed in FM12.
The issue with the body part size related to sliding has been around for a long time ( and probably still is)... I tested this extensively a while back ( I think it was version 9 )... Basically as you enlarged the body part it would prevent that area from being used for printing even though the part reduced. I got around this, when necessary by creating layouts with no body... I used sub-summary areas to take the place of the body and I would set a sort on the ID so I would get a break at every record. This had the advantage of being able to control the option of a summary vs a detailed report from within a script using the same layout. Simply not sorting by ID gives you a summary report. The sub-summaries seemed to slide/reduce with no problems.
Another issue along these lines... In Windows a text area would not display accurate "WYSIWYG" positioning when viewed at 100%. If you swithched to 150% or 75% it seemed to be fine. I am not sure if this is a Windows issue or a FM issue... But the problem did not occur on the Mac. I think it may be related to text kerning, It is not always obvious but gets more pronounced in large bodies of text.
if you reasd my post:
I also found that Windows and Mac behave differently