CRM 5.0 Installation with MS-SQL and windows 2003 server

Hi,

I have to install CRM 5.0 with MS-SQL 2005 and ECC 6.0 with Oracle 10g and integrate with QAS(Third party tool).

My question are:

1.Can we install all there application on single server.

2. what s/w units we have to chose generally and what are standard(ie. EP,TREX etc.....)

3.Can we install the s/w units later after CRM core installation.

I am a BASIS Consulatnt and first time installing the CRM.

Regards

Alok