Best Practises For Server Sizing For MS Reporting Services

We are planning to deploy the MS Reporting Services. Unfortunately,
there isn't much guidance on how to effectively size a server.

Here are my questions:

1) In an environment with 1 reporting server (hosting the reporting
data layer, application, and management layer) connecting to 1 or more
SQL servers (over 2 trunked 1Gbps switches connections), what is the
constraining resource when running large reports against a database of
say 4GB in size? CPU, RAM, DISK, or Network speed on the Reporting
Server? Or the Data hosting SQL server? Or does it depend on code?
2) If I have a Duel Core CPU, do I buy 1 CPU license. MS had responded
to the HyperThreading as 2 virtual CPUs with the statement that you buy
CPU licenses based on socket count effectively. This would imply that
if I buy a 4 Duel Core AMD Opteron Proliant 585 (8 CPU cores in 4
packages / sockets), I can run MS Reporting Services Standard Edition.
Is that true?

Any input or direction would be appreciated.

Paul V.