Cognos PowerPlay 10.2 installation. Database for Content Store

[Ami]

Hello,

I would like to ask you some details about installation of IBM Cognos PowerPlay.

We prepare  migration from PowerPlay 7.4 to PowerPlay 10.2.0 for our customer.
This is small implementation: about 20 users, all PowerPlay components on the same server, data from two databases (IBM Informix IDS 11.50 UC9 (ODBC) and MS SQL 2008R2), simple reports, integration with Active Directory 2008.
My questions:

Question 1. About Content Store
We plan to prepare a new server with Microsoft Windows Server 2008 R2 SP1 with IIS 7.5 dedicated solely for use by PowerPlay 10.2.0. I take in consideration to possibilities for Content Store:
a.   Use database installed on another production server (MS SQL 2008R2). In this case Content Manager should have to use network connection to access Content Store.
b.   Install and use local database: MS SQL 2008 Express Edition
What is your suggestion?

Question 2. About hardware requirement
We plan to install Power Play 10.2 on a virtual server like this:

Operating system:   Microsoft Windows Server 2008 R2 SP1 Standard English 
RAM:   4 GB
Hard disc:   100 GB

I would like to hear you opinion especially about amount of RAM. Is it enough 4 GB for a small implementation of Power Play? (all components on the same server, 20 users)