Will addressing his probelm help him deal with it better the next time he loses his temper? I doubt it, if he's angry he's not going to remember any coversation that you have with him about not losing it is he. I think the best thing to do is if/when it happens again get in first with putting the phone down or walking away - but say that you will resume the conversation once he's calmed down as you can't discuss whatever the issue is whilst he's angry. You must remain calm though.
Is he moving into the new place on his own or with OW? This is a difficult one to answer as we're guessing his reaction, it could be seen as friendly or it could be seen as you 'muscling' in on something that's nothing to do with you. If relations between you aren't too bad at the moment why not send a text in advance offering to provide sandwiches?
You could say: I know that you'll be busy on sat would it help if I give the kids some sandwiches for you all to share for lunch? This may be too mothering though - not sure.
