1. It is possible for two to live together, but they should both be female, and even then sometimes they won't get along. Always be prepared to separate and house them separately.
2. I haven't bred any hedgies as I firmly believe it should be left to the very experienced experts, who can handle it.
3. Again, I don't recommend breeding in the slightest to new hedgie owners.
4. For two, that is definitely too small. If you wanted, you could get two tubs and attach them together for ambient space. For one, it is still a bit on the small side but, properly heated, I think would do.