I read that winter whites are among the friendliest of dwarf hamsters (at least it's on Wikipedia). It will always depend on individual hamster how friendly and sociable he/she is. You can get a tame roborovski or a wild campbell.
I'm in the U.S. too, and it's possible to get decent cages after some research. 10 gallon tank would be on the small side for dwarves, as they still are pretty active and could use the room to run around (+ room for toys, sand bath, wheels, etc.) I find that the minimum size cage for that is Ware Natural Wood Cage for Hamsters
. That's a great budget cage for 1-2 dwarves (but if you get roborovski hamsters, be sure they can't reach the bars with lower bedding until they get big enough so they can't easily escape through the bars). Once you put all the toys in, you can find that there's little room for the hamsters to run around, which is also why bigger cages are nice.
You should have 2 wheels, and you can have 1 of each for the rest : big flatter food dish so both hams can fit at the same time, one big house should be fine if your hams get along well enough, various toys to share. Avoid tubes and separated levels and pods for more than one hamster. 6.5" wheels are good for most dwarf hamsters. Small roborovskis could use 4.5" to 6.5".
I hear male or female doesn't matter too much.
For houses, pick something at least ~5" diameter for 2 hamsters. The wooden house that comes with the cage I linked is a good size, for example.