i have never done one before and am intrigued... I was wondering would either be able to be applied to the side of the cake instead of the top ? or would it slide off or something?

I am planning on making a little einstein's cake for a bday and thinking of ways to do the characters on the side of the cake since the rocket will be on top.......

any help would be appreciated

I think that would work fine - you could apply them when the icing is still 'wet' or use RI or BC to attach them. I've done them quite a bit with no issue! (Did a Little Einteins cake a few yrs back for my son - one of my favs! Didn't do the characters, though...Rocket and music notes all over! Hadn't figured out about the transfers yet!)

Oh, another thought: Make your choc transfers, when cooled, mount on a 'bed' of white chocolate and attach a lolly stick to the back - you can stand them up on the cake, too...(did this on my Diego cake in my pics.)