Simple question. I have made IP firewall mangle rule that marks packets based on layer-7 regexp to make them higher priority than other traffic. Than I make rule under queue tree, that set priority for these packets as 2. Question is do I need to mark also all other traffic and set its priority number bigger than 2 or there are some default number for this traffic and such setup will work for me?

Good question, I don't know. It is easy enough to mark everything else though.

You need to (to my memory) queue everything. Not just one part of traffic.

As in, mark traffic that matches your regex match and then mark all other traffic.

Set up your queues to allow for your regex marked traffic to have more priority than your other traffic.

Setting up the numbers in priority means which queue will be serviced first to the configured limit you have for it.