The only two ways to get from Lima to Tahiti are
1. LAN Lima-Santiago-Easter Island-Tahiti (21hrs not daily)
2 LAN Lima-Los Angeles then Air France / Air Tahiti Nui LA - Tahiti (24hrs)
Based on that I'd suggest spitting it into two separate trips
In Cuzco, I stayed at Palacio, and would go to JW if I went back.