First metric century in August. No bike yet, not much experience and I'm only 17. Any training tips or race etiquette tips?

I work as a lifeguard and last year rode 10 miles one way to get to work. Toward the end of the season a reckless driver ran me into a ditch and kind of trashed the bike. Lately I've been riding on an indoor exercise bike (Gold's Gym Power 290 Upright Bike) for about an hour a day starting on a performance workout for a half hour then I do the fat burner as a bit of a cool down. Also any recommended bikes for someone on minimum wage would be awesome. Love seeing the bikes and seeing the true passion for biking here on Reddit!