Question about SAP PPM 6.1 Installation

Hello experts,

We will deploy SAP PPM 6.1 recently.

As I get the installation information from SAP PPM 6.1 master guide for the minimal system landscape (we have SAP ERP 6.0 EHP5 installed)

Question 1: We need to install NetWeaver 7.4 with addon PPM and business foundation, and SAP NW Adobe Document Service, right?

Question 2: Can we just install ADS and NW ABAP in one physical server?

Question 3: For our ERP we have three system, now we also need to installed three system landscape?

Thanks & Best Regards,

Tong Ning