SAP Solution Manager 7.2 Installation

Hello,

I am planning to install Solution Manager 7.2 system and as part of the preparation I was going through the master and install guides. After doing a lot of reading I still have some doubts

1) In Solution Manager 7.2,  do I have to install ABAP and JAVA stack separately? Does Solution Manager 7.2 has an option to install dual stack              

    (ABAP+JAVA)?

2)  If yes, how do I connect them?

3) Is it mandatory to configure/activate Solution Documentation? If yes, is it mandatory to install TREX?

Thanks,

NB