Hello, Pedro.
1. You can export WSDL as a file and provide it to a 'consumer' without a direct connection to the system. You should avoid to grant unauthorized access to the system. So there is no possibility to create 'anonymous' access here.
You can take a look at your web service (which you've created in web service tool) definition in SE80 in Enterprise Services (in Object selection dialog). There is a Configuration tab. And under Security profile - Authentication you can see there are only two options: Basic and Strong authentication. The same is available when you are creating a web service in the web service tool and setting up security profile on the last step. It is hardcoded. And for good reason.
2. SOAMANAGER can be perfectly used without Java stack and without PI instance.