Can I use HTTP POSTs? Is there a better alternative?

WordPress is an HTTP/PHP web application. The ordinary rules of HTTP and PHP apply, and work. WordPress itself uses $_POST and $_GET more times than I can count. If you want to pass information from one page to another– say from a form to a search handler– you have to use one or the other.

There are some helper functions like add_query_arg() that might be applicable but as written your question is too broad to allow for specifics.