BE6K small is a blade server that is hosted by an ISR router. While other versions BE6K M and H are UCS C220 servers.
Refer to below:

Ordering guide: Go through ordering guide its particularly helpful in understanding the platform, licenses and how to order.
http://www.cisco.com/c/dam/en/us/products/collateral/unified-communications/business-edition-6000/guide-c07-717328.pdf
Datasheet: http://www.cisco.com/c/en/us/products/collateral/unified-communications/business-edition-6000/data_sheet_c78-717454.html
Cisco PA: http://www.cisco.com/c/dam/en/us/td/docs/solutions/PA/midmarket/collab.pdf
Design Zone: http://www.cisco.com/c/en/us/solutions/enterprise/design-zone-collaboration/index.html
Also go through SRND 10.X (at a later stage once you have selected a platform)
If you go through above information you will have sufficient information to design/deploy the BE 6k.
Consider the BE6K medium as well, to account for any growth etc. and its a full UCS C220 server. Just a suggestion but make a selection based on your needs.
-Terry
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