Soap Adapter (What info needs to be provided to the Third Party Developer)

I have the following scenario

Third Party --> Soap Adapter --> XI --> IdocAdapter --> R3

My specific question is, what information do I need to provide to the Third Party team in order for them to successfully send a message to XI. (Note that I am using SOAP Adapter)

1. What is the URL that they will need? the syntax/format?

2. Do I need to provide a userid and pwd and if so, which userid is normally used.

3. I think I will need to provide the WSDL also ( I have already generated this). Is this right ?

4. Any other information that they will need from me.

Thanks in advance for your responses.

- Ravi