they have a lower tonality--they won't have a "white" detail really. It's more of a mid to low gray level. You can copy a tintype onto ortho film rather well, actually--toss a grayscale in there, and pump up the development to increase the contrast. You can then turn around and print it onto modern paper and get a full scale image actually--one that is deceiving. It will look more like a b/w print than a tintype, because you've expanded the tones.
They can also be deceiving in that, tintypes were often handcolored, as were ambrotypes. If they're housed in a case, they can sometimes look from a distance like an ambrotype. The daguerrotype looks less like these other two--it's hard to mistake that, since it will only look like a positive from a narrow angle, otherwise it's like a mirror. The only way to really copy a daguerrotype is to shoot it on a view camera and use a combination of movements and black cards to control the lighting and reflections. The union cases present their own challenge as well, since they were made of wood, leather, velvet, glass and had some ornate frames. But, you can copy an ambrotype in much the same way, only by shooting it head on through a black card...the daguerrotype needs to be shot an angle, with the card cutting the reflection, and the front & rear movements correcting the perspective...
I've had to copy all three types quite frequently for the museum I work for...when it comes to caring for them, well, that would depend on what shape they're in now. A conservator or maybe an archivist could give you some tips about this--if you have a history museum, archive, geneological society etc in your area--check with them. Most public institutions will offer advice to their patrons as a service. If you have access to such a place, take them up on it.
good luck & hopes this helps
my opinions only as always/not my employers.
