2 and 3 are both definitely problems, and for the same reason; it's important that when the same language is used for different effects they work the same way. The two effects on the Shield Spirit both use the same language to describe when they activate, therefore they need to both activate under the same conditions. If the player had an item with the same text as the Elder Mage's ability, it would cause them to dodge every second damage source in a turn, not all but the first; therefore the Elder Mage's ability should work that way too. Consistent use of language in effect descriptions is vital to a game like this.
The issue with vampirism counting as a separate damage source isn't technically a bug, it just causes problematic interactions due to ordering (and changing the order in which the damage sources trigger doesn't solve it, it just changes which specific situations have problematic interactions). If it were me, I would change vampirism X from "deals X damage and heals for unblocked damage dealt" to "this item heals for unblocked damage dealt up to a maximum of X" and give most or all of the items with vampirism X an additional +X damage bonus (that would keep the total damage and potential healing the same, but unifies the damage into a single damage source - technically a small buff, but much more consistent in its behavior).