Configure Apche 2 for both private and public networks

I have Apache2 installed and have the following requirements:

- For connections initiated from outside, the first static page will
be connected via HTTP and the subsequent pages will be connected via
HTTPS
- For connections initiated from inside, all the pages will be
connected via HTTP.

Is there an easy way to configure httpd.conf to do this?

I can imagine using VirtualHosts: one for external and one for
internal. However, if I only have one 1 physical network interface on
the server and have a firewall doing NATting for its real external IP,
will it work if I specify the server's real external IP in
<VirtualHost ..> directive?

Also, for requests from outside, how do I "redirect" the initial page
via HTTP to subsequent HTTPS pages? All the links in the initial
static page have relative path.

Thanks,