I'm working on a landscape 11x8.5 book to have printed by a commercial printer. I have set my margins on all sides at 0.75 inches. I'm not having any pictures or text that will bleed on the pages. What should I set my numbers for bleeds and slug to?
You can set them to whatever you like.
You can always include the bleed or the slug area on PDF export.
If you think it might at some point have images that bleed or a background that bleeds - then you are already setup.
The slug area is only for information traditionally communicated with a 3rd party, like a printers with specific requirements, or perhaps an infotable with some information relating to the project.
However, these are all optional on export to PDF.
Personally, if you don't need a slug area, don't make one.
If you have bleed or not - I'd include it in the document as standard practice.