1. How can I have grid lines displayed
Well, if you take the preview of the excel file sheet in MS Excel (Click File|Print Preview), you will see that there is no gridlines which you normally see in the Excel environment, it's just for display purpose and for identification and managing each cell's value separately for a user. I think you may add/set borders around the cells for your data in the worksheet. You can manually set borders in MS Excel or use Aspose.Cells APIs to apply borders before saving the .xml file (Aspose.Pdf Integrated file), check the following topics for your reference:
2. How can I tell it that it has more space to render the columns because it is in landscape..
Well, when you convert and excel file to .pdf file with landscape pagesetup attribute, Aspose.Cells try to document the corresponding pages height and width accordingly but you might not get exactly the same landscape settings for the page(s) when the file is rendered to .pdf file format as both Excel and Pdf are different architectures and having their own sets of attributes. We always try to mimic the similar results converting to .pdf file formats.
I think you may try some pagesetup attributes using the Aspose.Cells APIs
e.g.., PageSetup.FitToPagesWide = 1 etc. and further check: http://www.aspose.com/documentation/file-format-components/aspose.cells-for-.net-and-java/setting-page-options.html
If you still find any issue, kindly post your desired template excel file, we will check the conversion.