Building a portal using SharePoint 2010

Question

Hi,
We are trying to build a portal using SharePoint 2010. 
The pimary requirement for the portal is to allow users to upload, view and manage different types of documents (xls, doc, ppt, vsd).
The uploaded documents need to be mapped to the different categories as per their classification. 
For example, the documents fall into 5 main categories: A, B, C, D, E. These categories are further divided into sub-categories and so on for two more levels.
Example, Main categories: A, B, C, D, E
Sub categories for A: 1, 2, 3, 4, 5 and so on
So, if one clicks on node A and then click on node 4, then all related documents will be displayed. (A.4)
From the front end point of view, the user should be able to access these documents by just clicking on the nodes representing different categories.
There are some more functionalities to be built for this portal - search, versioning, etc.
Can someone please provide me the (high level steps) approach for building this portal and some reference material from features/architecture/technical requirements point of view? 
This would of great help!
Thanks!

Answer 1

Sure. Most of what you're describing is around the topic of document storage.
As you may be aware the object documents are stored in within SharePoint is a document library. You can have sub folders within that library but they're to be avoided if possible and shouldn't be a default choice.
To classify your documents there is several routes you can take. The least complicated is to use a single Content Type with a single Managed Metadata Column. This column would use a Mananged Metadata Term taken from a term set with the structure of A (1,2,3,4,5),B(x,y,z),etc..
That will allow your users to tag the document on upload (or modify it later) with a term such as A:1 or B:52.
To browse only the relevant items you can use the Managed Navigation tools in the document library, this allows you to show a term set and filter to various levels, for example all A terms, (ie A:1, A:2 etc.) or drill down to A:1 specifically.
Reading list:
Intro to Managed Metadata:
http://office.microsoft.com/en-gb/office365-sharepoint-online-enterprise-help/introduction-to-managed-metadata-HA102832521.aspx
Metadata navigation for a list or library:
http://office.microsoft.com/en-gb/sharepoint-server-help/configure-metadata-navigation-for-a-list-or-library-HA101820113.aspx
Optional Extras:
Intro to content types:
http://msdn.microsoft.com/en-us/library/ms472236%28v=office.14%29.aspx