A good SOAP library lets you plug in a WSDL and returns an API object with all the methods of the webservice. There is literally no equivalent capability for REST. You shouldn't be doing any of the things you describe by hand.

You are vastly oversimplifying when you say "with REST you just have to figure out a URL". Try integrating with a service that takes only custom HTTP verbs with multipart/form-data but because there's no standard way to send an array in HTTP you have to append some parameter multiple times but in the right order. There's some vague attempt at using OAuth for authentication, but it doesn't work with any of the libraries you are used to. Oh, and the service returns a 503 some of the time, which (according to the rambling hacked up docs for this API) means you should retry your request in 10 seconds. No, it's not always trivial.