Lastly, don't be afraid to ask about safety: Any reputable operator should have safety information prominently featured on their website, and won't mind answering questions about their pilots, such as how many hours they have flown. (At least 250 hours, which is what it takes to get a commercial license; NetJets mandates at least 2,500 hours; Wheels Up, mandates 7,000 hours for a captain and 4,000 for a first officer.) Gollan suggests fliers ask if the pilot has any health issues, and feel free to ask if the operator (or plane itself) have any accidents or incidents in its history.
Though the early Lockheed Jetstar had four, most production business jets have two jet engines, mostly rear-mounted podded engine. If mounted below their low wing, it wouldn't allow sufficient engine clearance without a too long landing gear. The HondaJet is the exception with its over the wing engine pods. Dassault Falcon still builds three-engine models derived from the Falcon 50, and the very light jet market has seen several single-engine design concepts and the introduction of the Cirrus Vision SF50 in 2016.