Some various rule points and PBF expediation notes.
1) There are three black/city cards (one per age) whose effect is copying a science symbol from a neighbouring cities green cards (I'll call them mask cards from now on). These can only choose a specific green card in a specific neighbour's city once, if you have two or more mask cards. So e.g. you could copy a Gear from a Workshop on your left neighbour AND one from a Workshop on your right neighbour, but you couldn't copy a single Workshop twice (e.g. if it was the only green card either of your neighbours built).
2) A more important point.
Unless you request otherwise or cannot afford it, I will always assume you pay debt by discarding coins. The main issue here is that most people will probably have their next hand by the time you'd need to decide otherwise, and it could seriously affect your choice seeing that.
I realise Halikarnassos (and now Rome) has essentially had the same issue, when it builds a wonder stage. With Halikarnassos I don't think it makes much difference, as the card he plays is free, but maybe with Rome it could affect things. We could fix this in two ways. 1) I always send these wonders their hands when they've reached the point that they can build their wonder stages. Or 2) We just don't care, those wonders become slightly stronger, but certainly not enough to be overpowered in my opinion.
Update whenever you pick a leader or forward your hand on. Only forward the hand on when the person below you has picked their next leader! When you have received your 4th leader, please select your first leader play.
Kuildeous: Hand 2 received. 2 picked.
eHalcyon - Hand 3 received. 3 picked.
Galzria - Hand 4 received. 4 picked. First leader not played.
mith - Hand 3 received. 2 picked.
Qvist - Hand 1 received. 0 picked.
Davio - Hand 1 received. 0 picked.
Insomniac - Hand 1 received. 1 picked.