Re: About new classes, what is the best thing?
I think it is ok to include them in the same assemblies but I would create new classes. For example don't put your custom data access code in dbPortal.cs, create a new class in the data project. This way if you later want to separate them into their own assemblies it will be easy.
Also this will avoid problems when you want to get the latest mojoportal code using SVN Update.
You may sometimes get a conflict when svn tries to merge the changes in the .csproj files. In this case you could let the version from svn win and then just right click your classes to include them back in the project after the update. Most of the time it should be ableto merge them without conflicts.
Hope it helps,