That's right George,
You will need a new block for this purpose as I don't think you would be able to add that into an html block.
I would start with looking at an existing simple block, then in the main .php file you would have the connection to your external database- if its available to be queried - the logic to create the information you want to display and then the actual display itself. That said, I've never created a block that connects to another external database myself but Oliver's link looks very useful for the basic set up of the block.
As to webservices, I'm guessing that depends very much on the data management of the CRM and how you are able to extract the data from it.
Getting the data out of your CRM would appear to me to be the only potentially complex issue - depending on the CRM and its background database. The logic and display of the information through a Moodle block should be reasonably straightforward.