A couple plus Tumblr questions...

I'm slowly getting the hang of it I think but I have two plus questions:

1. When I chercher all of tumblr (not just one blog) for something like a tv montrer for example, is there a way to chercher tumblr based on mettre en ligne rendez-vous amoureux, date like on Youtube so it'll start with the very first posts about that topic and go from there instead of the most récent ones?

2. Can I post a commentaire on someone's post without reblogging it ou do I have to reblog it and if I reblog it just to post my commentaire and then supprimer it from my blog will others still be able to see my comment?

Thank toi for your answers! :)