How can I change the EPT for a project using PSI?

Hi:

Actually I have 3 questions related to PSI (I'm new to .Net programming):

1. How can I change the Enterprise Project Type of a project (from 'Sample Proposal' to 'Basic Project Plan' for example) using PSI?

2. How can I change a Custom Enterprise Field value for a project (that point to a Lookup Table)?

3. Can I use Visual Studio 2010 Express to do this?

On the other hand, is there any tool available to modify the value of a field for a list of projects in PWA?.

Thank you very much

Regards

Carlos Negroni