No personal experience with that P0463 code, but after reading the doc, I'm not understanding how a fuel level sensor high voltage is being caused by a bad fuel pump. And since the pump is over $200, you should do fuel pressure testing before hanging on one of those. Has the throttle body ever been cleaned? This a fairly easy DIY job, and you also should consider removing and cleaning the TPS and IAC (either of which could be causing the P0300 at low revs), as a part of that cleaning. If that helps but not all the way, then maybe replace one or both of those parts (around $25 and $50 respectively).