Trolling comments are not useful, if you do not know the product or have nothing constructive to add do not comment.
If you look at 'jarda's' amount of posts it looks to me he is a more advanced user than you.... his remark is valid, why post a tread twice? 'Because you get no answer quick on the first?' Well, maybe the question is to obvious in its answer nobody bothers to reply.....
Secondly, to help you in the right direction; you can easy block the ping command without blocking anything else. 'ping' has specific port number.
Third, I am pinging many routers continuously. Some are pinged from different routes. As long as the packages are small and you don't flood the router with thousands per second the traffic won't notice it....
And the WAN port? Well, many robots or ports scanners are continuously sending ping commands to our WAN ports. There is no way to stop this since its 3rd party. All you can do is filter or block it.
There are several example in the Wiki and manual on how to do this....