The problem was you did not rebuild the whole solution or else you had build errors, you only built mojoPortal.Web and its dependencies the first time. The needed files for other features are copied by post build events in the other projects so if they were not built then the files would not be copied and the features would not be available.
The only project that you should run in the browser is mojoPortal.Web, it should be the startup project. You can disable other Web projects from launching instances if the VS web server from VS Solution Explorer, click the mojoPortal.Features.UI project node then click the Properties tab on the right side of Solution Explorer (not the same as right clicking the project and choosing properties), there you will see a setting for "Always Start When Debugging", you can set it to false and it won't launch a web server for that project. Unfortunately these settings are saved per user not in the global project settings or I would disable them by default.
Hope it helps,
Joe