How do I get dynamic parameters into the array,…
This example from the Codex demonstrates that:
$paged = get_query_var( 'paged' ) ? get_query_var( 'paged' ) : 1;
$sticky = get_option( 'sticky_posts' );
$args = array(
'cat' => 3,
'ignore_sticky_posts' => 1,
'post__not_in' => $sticky,
'paged' => $paged
);
$query = new WP_Query( $args );
Both $paged and $sticky are variables– I assume that is what you mean by ‘dynamic parameters’.
or where can I find the rules for parameters in string format like my code?
Not entirely sure what this means but the Codex page for WP_Query should give you all the parameters. You seem to know how to create that query-string-like string, but I encourage you not to. Build an array and use that. That string is hard to read. It is hard to edit. And it probably doesn’t work with the more complicated queries, like the meta_query, but on that I am really not sure since I never, ever use that string syntax.