I need to accomplish the following from within a button on the accounts page:

take customer account address

send SOAP request with address

receive SOAP response

update salesforce account information depending upon response

I am a bit overwhelmed with trying to plot out the best way to accomplish this.  The salesforce developer library is so powerful I don't know where to begin. 

It seems there are a number of ways I could do this, either through a visualforce page which I assume would easily be able to update the data, but I am unsure of how to embed a SOAP request and parsing the response, or via an externally linked page, which would then update the salesforce via an API after the response has been parsed.  Any thoughts would be greatly appreciated.