Moving to MySQL is probably not a cost-effective solution.  The problem is that we do not offer a free-runtime on the MySQL platform.  The reason we do not is because we cannot encrypt the SQL code in MySQL.  So, if you were to migrate to MySQL, you would have to pay $400 per CRM user.  We do make exceptions to this if you are hosting provider as your customers would not have access to the SQL code, but if you are planning to deliver a CRM on-site to the three-subsidiaries, then you would need a per user license across them all.

The free-runtime is intended to allow a System Integrator to build a profitable business around SplendidCRM.  The key to the license is that the System Integrator only pays for internal users/employees of the CRM.  Your situation is a little different, but the key to understanding if you qualify for the free-runtime is to ensure that the subsidiaries are separate legal entities with separate payroll systems.  If the subsidiaries have a common payroll, then the users are internal and you would have to pay the $200 per user fee.

If your goal is to save on SQL Server costs, your best bet is to use the free SQL Server 2005 Express product.  If you exceed the limitations of SQL Server 2005 Express, then the next best option is SQL Server 2005 Standard Edition 64-bit. 

Regarding the three large projects, so long as you meet the System Integrator requirement and you deploy the applications with the SQL code encrypted, then you would not need any additional licenses.

The Outlook Plug-in may be distributed to any use of SplendidCRM without any additional fees.

One final note.  We are planning to rearrange our licensing model so that we can offer something under GPLv3.  We will likely change the terms of our Professional license to compensate, but it would not affect the terms of any existing license.