SQL Server 2008 Standard R2 Installation files.

Hi,

I recently acquired a server with SQL Server 2008 R2 (Cloud Services- SoftLayer) to upgrade my current production machine (from sql 2005). Even though I asked them to install it with a named instance, they installed a default instance of SQL server. 

Now I need to add another instance to match my existing system and product licenses but they did not save a backup copy of the installation files. That brings me to my question. 3 in fact.

1. Where can I download the installation files / ISO for SQL 2008 R2 ?
2. Can I use the setup files from the Evaluation ISO provided by Microsoft and still have a licensed copy?
3. Should I just modify my existing production software to run with the default instance of SQL?