1) I think you can do most of the caffeine free herbal teas, although it's better if you stick to peppermint because it neutralizes the toxins... but I guess from time to time you can vary, just don't abuse.
2) Gum is not allowed because it keeps your digestive system active, will probably give you more hunger pains, and on top of all that it has so many chemicals that you'll be putting back in your system all the toxins you're trying to get rid of.
3) I'm not sure about this last question but from what I've read people tend to stick with lemons and limes while on the MC. You can combine these two as you please. And regarding the OJ while breaking the fast... Maybe on the 2nd or 3rd it won't do you any harm combining different types of oranges. But I think someone with more experience than me should give you more info on this issue