1. Not true, necessarily. They can be targeted just like any other cards, they just have to meet the criteria. "Evil card" or "evil character" both work for demons, as do "good card" or "hero" for angels. However, if they target "humans" specifically, then the card does not target angels or demons. The same is true if a particular gender is targeted, and that gender is not represented by the card (yes, almost all angels and demons are either male or female, and almost all are male for reference).
Basically, does the card fit the description of the target and is in the area able to be targeted? Then it is targetable. There is no special case just for angels or demons.
2. It is a temple artifact, and only a temple artifact. It can currently go in any temple. You may not place it in the Tabernacle.