We have a SQL Server 2008 Enterprise database with two different schemas, a locked one that we maintain and an open one that we allow outside development teams to add to and
The Redgate options are as follows.
1) The easiest way you can start auditing schema changes is by installing DLM Dashboard. This is a free tool that alerts and logs all changes using DDL triggers, and will include the information you ask for.
2) As is already mentioned by Andy Davies, the right way to do this is to start source controlling your schema in the same way as you do for application code. Once you've done this, you can increase your database lifecycle management maturity by including your database in continuous integration and release management practices.