I'm no great expert, but I'll give my penny's worth.
#1 From the reverse you can tell this is a Fel Temp fallen Horseman type. These were issued from 348 onwards. From the obverse you can tell from the headbands that it is an Emperor not a Caesar and so that leaves only Constans or Constantius. Constans' Fallen Horsemen are very few and far between and so the probability is that it is Constantius.
#2 This is a Vota coin and again the choice is between Constans and Constantius. The portrait looks slightly more like the first rather than the second, but it is difficult to distinguish them.
#3 This is a Salus Reipublicae type issued by Theodosius and his sons. I think I see an N and an O, so it could be Honorius, but it might be easier to see in hand.
