How many suns are around Starkiller base in the Force Awakens? Is it just one? If its sucks the power out of one star from the back of the planet how is the front of the planet lit up like the sun is shinning on it when the Rebels attack it? If the weapon is charged shouldn't the plant be in the dark?
The Starkiller Base system (initally) has a single star. This is confirmed in the film's Official Novelisation.
Given the chance, she would have remained in the medbay, where the Wookiee set his burden down. But despite its added modifications, the Falcon still flew better with someone in the copilot’s seat. In moments they were beyond the atmosphere of the imploding planet. The jump to lightspeed was accomplished without incident, preventing them from observing the final cataclysm. Which was just as well. A moment after they fled, Starkiller Base system became a binary.
As to how they're able to fire a second shot, I suggest you have a read of this question/answer set