I'm having a little trouble visualizing the first issue you describe. Does this happen only on the first page or on all pages except the first page? Can you attach an image that demonstrates this gap?
For the 2nd issue, could this thick line be the table borders for empty rows instead of 1 solid line? For example, if I had 100 empty rows and the auto height set to to a small minimum height, it might appear that there was a large solid line when in reality it was just 100 small border lines stacked on top of each other.
Just a thought, something to investigate.
Thanks
Jb