Prep concrete for tile, after linoleum?

[Skunksmash]

Hi all. I know this isn't a DIY home improvement forum, but I know a lot of you guys are big DIY'ers. I took the old linoleum off my bathroom floor. And I am getting ready to lay tile. So here are a couple of questions and pics.

1. How exactly do I prep the floor for tile? Seeing as how there used to be linoleum. As you can see from the pics, the old linoleum glue is still there. Should I somehow sand that off? Or put some kind of chemical on there?

2. I'd like to use some self leveling compound on the floor, if it turns out its necessary once I check with a straight edge. But there is already some old leveling compound on the floor, where someone else did it. Its somewhat broken up though, which happened when I was taking up the linoleum. Can I just pour new compound over the old stuff? And what kind of edge will the compound leave? I wouldn't want my tile to be unlevel.