I can answer those for you, but it really sounds like you are asking for more functionality than the Toolset can give you. As I will mention below, our Orion product would probably be a better fit your your requirements. Here is a demo...
Is there a limit to the number of gauges I can auto publish to the web?
Yes - 31 Gauges. Orion has no limit.
Must all gauges be published as one tab/unit?
Yes - we only support exporting to HTML for one instance of the application. But Orion will show you interface gauges for thousands of devices.
Can I autopublish multiple tabs of gauges?
No, but (yeah, you know what's coming...)
If I have a tab with a gauge and a chart will both the gauge and chart be published be published together?
No, but Orion not only does gauges, it does really good charts too.
Will anyone be able to access the items published to web or is there any security, ie user/password requirement?
Our publish to web does not actually create a website, it just creates an HTML file, with image tags for the gauge representations, and images for the gauges. Orion has a secure, fully configurable /customizable website with multiple security levels, and the ability to restrict users to viewing only those device you want them to see.
"Yes - we only support exporting to HTML for one instance of the application. But Orion will show you interface gauges for thousands of devices."
Does this mean if I export gauges to HTML I can not export charts?
Grant - That is correct, the Bandwidth Gauge does not export the chart.