Paige uses the power to heal on Cole after only being aware of her powers as a witch and whitelighter for one day. She seemingly forgets how easily she could access this power, because she doesn't use it again for many episodes. In the season 6 premiere Valhalley of the Dolls, she even admits out loud that she can't heal, explaining that it is difficult because she is only half whitelighter.
Leo and Cole say that good and evil have agreed on a 48 hour window for someone to be swayed to either good or evil, thus the source is trying to lure Paige to evil. However, when Prue, Piper, and Phoebe first received their powers, no one tried to lure them to evil. Piper was afraid they were evil, but in the end it was understood that they were good witches.
When Paige is talking to her uncle on the phone, they both say the nun found Paige, as though she was left abandoned. But when Paige talks to the nun, she says Paige's parents appeared and gave Paige to her.