An Excel to pdf question

[Ulodesk]

I hope this is adequately germane to the forum.
I had to pdf a received Excel worksheet today. Originally formatted to a landscape page of undetermined size (as far as I could see), the data was taking only a small corner. I selected the data and reset the print area, then used Layout to change the page to portrait letter size, and set the size to 1 page by 1 page, which resulted in a "magnification" of 74%.
When I saved as a PDF it looked fine, except that the part of the header in the right-hand box stuck out beyond the margin of the text. When I inserted the page into another, letter-sized pdf, the page size of the inserted page showed as larger.
I tried opening the print dialogue for the single page pdf, only to find the preview showing the actual page size to be 11.5x14.9, with the 8.5x11 section shown inside a wide gray preview border.
I tried printing the Excel sheet to pdf instead of saving it to pdf, but the document stopped responding both times I tried.
What am I missing here? Is there a way to get the Excel header back in line with the rest of the worksheet? And why did the length as well as the width demand a larger page size when I set letter size?

Thanks.