There is a marathon at the end of the race afterall. Expect to run 3-4 days per week in training, and put hundreds of miles on (several) pairs of shoes. A good rotation of training shoes will get you to the start line.

You CAN use a road bike and slap some aero bars on the ends, but likely - you'll be looking at a tri-bike. Different geometry & placement of gears on the aero bars help make these bikes a bit faster over the 112 mile ride.

Wetsuits not only keep you warm, but they actually keep you on top of the water. A good wetsuit lifts the legs & hips on top of the water to reduce drag, and make you faster (with less effort) over the 2.4 mile swim.

To speed things up in transition, a belt that houses your bib and some energy gels can reduce your transition time. It can do so substantially if you had intended to safety pin the bib on in transition!