Configure redirect with DynDNS and port forwarding rule on router

Hello!
I have successfully setup Nginx on my Raspi.
However I'm failing with the correct configuration that feed my needs.

On the webserver I will provide different services, e.g. Owncloud and Piwigo.
Based on the configuration provided by Owncloud
(http://doc.owncloud.org/server/4.5/admin_manual/installation.html#manual-installation)
there's a redirect http to https.

I like this idea, however the following functions should be met for me:
1. As I'm using a DynDNS Server Account, I have setup a port forwarding rule in my router, means anything comming in on https-port 443 will be forwarded to the webserver IP port 443.
2. When accessing the webserver from internet, the following address should be redirected:
https://owncloud.<dyndns>.com -> Owncloud webservice
https://piwigo.<dyndns>.com -> Piwigo webservice
How should the relevant configuration look like?
3. If the redirect outlined above is not feasible, would this work?
https://<dyndns>.com/owncloud -> Owncloud webservice
https://<dyndns>.com/piwigo -> Owncloud webservice
How should the relevant configuration look like?
4. For the redirect http to https is it required to setup another port forwarding rule in the router?

THX