Yes. All you need is the wsdl file of java web service so that you can create the proxy and then use it to call its web methods
Yes without any problem. Its same as we can make request from Asp.Net Web Application to a WebApplication /Server which based on java. We only have to make a request which is understandable for the target webservice. We can parse the response and tranform i example into information by using standard XML manipulation classes in .Net. Bottom Line
Yes.Actually Web services are independent to language. it depends on WSDL and SOAP. so any one can develope the Webservices anddisclose the wsdl and users can cosume the web services.WSDL and SOAP both are xml based.. And all languages having xml parsing capability and access to http protocol will be able to work with Webservices.