OK well for the babies I really like the idea others have suggested before that instead of a 'normal' time out, put them in a playpen so that they are contained and not allowed to play. NO TOYS and keep doing it until they get it. This way you don't have to worry about them wandering off etc. If you have to set up two of them! They need constant reminders not to touch/hit etc. I'd also keep the 'biter' busy with his hands, like colouring, lego so that he's focused on something. Distractions also help, if you find that during free play they are acting up and all you're doing is saying no no no no then turn on music and start singing. Get their minds off the "naughty train".

As for the 2.5 year old, you said he JUST started with you. I bet he is still getting comfortable with you, it takes a while, so being exposed to potty is a big deal to them. I got a egg timer from the dollar store and set it to 45min-1hr to remind me & the child it's a potty break! Sometimes they didn't have to go but it was a way to keep me on track and gives them a chance to tell you yes or no....for now.