Question about danios and the safety of my young fish?

I just got 5 juvenile rainbow shiners for my 20g, and they're currently acclimating and pretty much ready to go into the tank. However, I have a few quick questions. First, the smallest of them is only about 3/4" long, and I currently have two danios in the tank. The danios are going to be moved (as soon as I can catch them...), but I just wanted to make sure it was safe to put my shiners in the tank now--the danios won't try to eat it, will they? I tend to doubt it, since I think it's a bit too big, but I just wanted to be sure. I also have some corys in the tank--they won't try to eat it either, will they? Again, I doubt it, I'm just paranoid.

Second, A few of them are just small enough to fit through the slits on the filter intake. I can't imagine the suction is very strong, but I just wanted to make sure my fish weren't in danger of being sucked in. I don't currently have any sponges or pantyhose handy, either, or I'd use those.

Third, I have the water temp at hair below 74 degrees right now. Does that sound about right?