The location of the web is determined by VS.NET by looking in the .webinfo file in the root of the web. It should point to http://localhost/mojoportal
The web won't build if the business or data layer doesn't build. Are you saying that the business and data layers both build just not the web? If you are using MS SQL you should remove the MySQLData project from the solution and check the reference under the mojoportal.Business project. If it has a reference to MySQLData, remove it and if it doesn't have a reference to MSSQLData add it as a project reference.
Are you getting a specific error?