When viewing the results of a cube view and using the Export to Excel button, the filename generated replaces spaces with "+" and adds "_Export" and the sheet/tab name of the file appears to be the cube view name. Is there a way to define these while still using the Export to Excel button? Perhaps a business rule attached in the cube view that defines them?
No, I don't believe there is any flexibility in that feature. Cube View Extender rules only come into play when exporting as PDF report, as far as I know. You might want to post on IdeaStream.
There are many ways to control Excel output (Books, Data Management exports, Table Views...), but they all require using something different from that button.