You can try something likes below.
CONFIGURATION SAMPLE
The following configuration sample disables the #exec command for SSI files in the Default Web Site.
<location path="Default Web Site">
<system.webServer>
<serverSideInclude ssiExecDisable="true" />
</system.webServer>
</location>
C# file looks like below
using System;
using System.Text;
using Microsoft.Web.Administration;
internal static class Sample
{
private static void Main()
{
using (ServerManager serverManager = new ServerManager())
{
Configuration config = serverManager.GetApplicationHostConfiguration();
ConfigurationSection serverSideIncludeSection = config.GetSection("system.webServer/serverSideInclude", "Default Web Site");
serverSideIncludeSection["ssiExecDisable"] = true;
serverManager.CommitChanges();
}
}
}
You can get more information Server Side Include
For your 2nd Question:
You can use Master page.Then all inherited pages will have both headers and Footers.
I hope this will help to you.