Altium: how to change document template font
You need to edit the SchDot (schematic document template) file if you want to change the font. If you are using a default template you should be able to find it in C:\Users\Public\Documents\Altium\[Version]\Templates. 

How do you set your page number text? If the SchDot is set up correctly you should be able to add your page number by using the Design -> Document Options -> Parameters dialog. My guess is there's an asterisk either hard-written into your template (unlikely) or you're setting your document number incorrectly and the asterisk is the default found in the location I just mentioned (Document Options -> Parameters). You should be able to clear it out from there.

Without giving us more information of how you have your template set up, this is about the best I can do to solve the problem.