A: Good question; unfortunately only you can answer that. SharePoint topologies can be very simple (a single-server intranet) or can become incredibly complex (a global, multi-lingual extranet with cross-farm services). Your business should understand the requirements and goals clearly and very early on in the planning phases, before financially committing yourself to any particular design. Ask yourself the following questions:
Who are my target end users?
What type of content am I exposing?
What is my budget?
What will it cost me to plan ahead and do the work now, rather than risk re-architecting later?
Would this topology be more optimal on-premise, hosted, or in the cloud?