A couple meer Tumblr questions...

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

1. When I zoek all of tumblr (not just one blog) for something like a tv toon for example, is there a way to zoek tumblr based on uploaden datum like on Youtube so it'll start with the very first posts about that topic and go from there instead of the most recent ones?

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

Thank u for your answers! :)