Thanks, the links helped, and I was able to solve the profile picture issue. I needed to add to the web.config:
<add name="ProfielPic" path="ProfilePic.ashx" verb="*" type="DotNetNuke.Services.UserProfile.UserProfilePicHandler, DotNetNuke" />
Is a bit confusing as the DNNStuff uses DnnImageHandler, which showed ok. Once I added in the ProfilePic, my Wiki images started showing.
Solved the picture, but the hyperlink to the profile is still not working (see the initial post). Would you have any suggestions on this? Also is it possible to use DisplayName (not FrstName, LastName)?