Cheers for the help everybody, After a quick Greek campaign to get used to phalanx units I understand them a lot more and have discovered what was happening to my men. I thought I'd post the results here in case anyone else has the same problem
situation 1) My warband intoxicated on routing an enemy unit swaps spears for swords to finish off the routing enemy, ignoring the fact that the routing unit has friends that are very much still up for a fight, at least they die happy (Ever wondered where they put the spears, since all they are wearing is a pair of trousers, yes I AM pleased to meat you). I don't feel to bad about this after seeing a Spartan unit do the same thing, though they were against a solo enemy unit at the time.
situation 2) Lord Edy was spot on with this (thanks for the general info on phalanx's as well) even though they are in formation already they sometimes decide decide to move around when ordered to attack (why oh why !) and get themselves in a mess.
situation 3) This may have been situation 1 again, but I think they did it before the enemy cav routed. Faction leader full charge 50+ heavy cav followed by Hastati broke my spear warband almost in half, the middle went from 4 ranks to 1 the entire unit switched to swords prob because unable to hold formation with no middle?
situation 4) My inexperience here, I couldn't understand why when in cities if I told a unit to move or attack they went straight out of phalanx formation and reformed at the destination and not moved in formation, even though there was plenty of room each side so there was no clipping. I got the impression that in a city if a unit isn't narrow enough to go through alleys then it will be considered to large to move for anywhere, even on the large main square, most annoying, especially as they can reform facing the wrong way.
situation 5) Routing units ran straight back through a phalanx, disrupting it enough that they fought the pursuing enemy with swords not spears. I didn't see if they started with spears and switched or started off with swords They should have just cut down the cowards.
Thanks again to everyone for helping