A few helpful tips...
R2 is composed of 2 parts, his dome and body. Be careful not to lift him out without securing both parts when you unbox.
His third leg slides up and down ("that's we she said" moment right there), but it sits in a tight groove that's plastic on plastic. It seems like a good place for a break to occur if you don't pull down evenly.
3PO has very strong magnets to hold his face to his head. When attaching them, do so with caution. When I first attached his face, the magnets literally pulled it out of my hands as I brought it closer to his head. Damn! That will easily crack the edges of his face if you're not careful.