1) https is really important if you collect personal data like shops do. Which zenphoto.org does not do (except the mail form and of course forum registration). However, the site will probably soon be https as we are about to migrate to a new host.
2) The forum will always be English only. In the past I did do some support in German but it caused seriously overhead translating back and forth if I needed to consult my non German speaking colleagues. But naturally German posts are not of use for all other users. English is the "Lingua franca" of our time that most likely the majority understands.
Same for the site itself, we really have no time to maintain any content in additional languages.