Blake, I am sure you have your reasons, which are yours alone. To answer your questions as best I can:
1: We can never truly know how and when the negative impact will affect us; We do know when we see the effects!
2: When anyone alters anything, it disrupts the ebb/ flow of Universal energy in some way. This is an inescapable fact. Some may disagree, but the energy transferred from one place to another leaves a gap, and that gap must draw energy from somewhere or someone else. Think of this as a checks-and-balances system the Universe employs to maintain its own energy. The consequence depends on your intent; Is it for purely selfish reasons, or are you doing this to help avert a potential disaster to help a loved one? Only you can answer this correctly.
Yes, there are such spells, but you might think this through so as to be prepared to face whatever consequence(s), good or bad that arise from this.