Hi most will tell you that they should be separated asap. I tend to agree with that wisdom, they will likely co habitat reasonable well but the downsides are if one is sick the other is suspect. It is impossible to keep accurate notes on defecation ect with two in one cage. I understand the space issue but I would try to find a resolution soon! If you are planning to breed you will have a bigger space issue at that point. Find a solution, racks or tubs new shelving but something.
Reading a snake is a challenge the s curve isn't always a prelude to a strike it can just be how she is sitting. Is she actively tongue flicking? A soft body and slower breathing is usually a relaxed posture, rapid breathing and tense muscles is not relaxed at all, the constant attempt to get away usually falls here too. The hunger response in my experience is being active roaming at night and sometimes dawn too. The sitting in ambush mode head out of hide just waiting can also be a signal of hunger, or not they are individuals I own a shy snake, an very inquisitive snake, a interested in new things but not too adventurous snake and a lap snake who will sit and chill for hours and make no attempt to leave. They all have differing responses to things.
I would really recommend some books,
www.reptileknowledge.com offers a nice ebook for a reasonable price. The ball Python manual Philippe De Vosjoli, Art of keeping snakes also be Philippe De Vosjoli, Ball Pythons by Bartlett and Bartlett are all good and fairly prices books that are easily available amazon I think has all of them.
Good Luck Hope this helps,
Alex