The coin dated 1781 appears to be an Austrian 2 ducat KM # 2087. I would suggest you weigh this coin ( it should weigh 7 grams )and if it does, possibly have it authenticated. For if genuine, it is valuable - $500 - $750. The item dated 1674 is not a coin. I suspect it is a commemorative medal or token, possibly struck in one of the Italian states. The date may be accurate - or not. As for the other, I have no idea but it appears to be an ancient of some sort.
Welcome aboard pilot. Unfortunately, I can't add anything to Doug's reply. (He's our resident expert on Austrian ducats.)
The other piece is a brass jeton issued by one of the ecclesiastical Austrian States (possibly Salzburg).
