There are some more approachs, like using CGI (Common Gate Interface), a library included in the Internet Toolkit, but these two approach are better.
I don't think so, but I don´t know. You must have the VI executing to can use the remote panel.
it is impossible. A web service is like a webpage, you send a request and the server send back a response, so if you want to update the state of the VI, you must to send a new request. I'm doing something like you want to do, and I´m using AJAX to maintain updated the states of the variables.
I can´t help you with this point, I don´t know nothing about this.
I suggest you to try to use a remote panel, is quicker and easier than web service, but if the VI is big, the remote panel can need more resources. If you want to use webservices, be careful because you only can recieve a response when the VI finished its ejecution, so you would have to modify the VI to break the loops.
PS: Sorry for my english, I hope you can understand it