If you want to get faster and stronger you should consider getting a cycling coach to guide you. You can read books, do lots of fast group rides, and try to improve your performance. But unless you really understand interval training, you'll likely not structure your workouts to meet your specific goals. A good coach will give you a weekly plan to give you structured workouts to focus on your weaknesses, taking you up the ladder one step at a time. The coach will also guide you on focusing on core exercises, whether in the gym or at home. I've been working with a coach for about 3 months and have enjoyed the structured workouts, rather than just riding hard most of the time, with some random intervals. You also need recovery weeks to improve and take some time off to let the body recover. I'd suggest exploring the coaching if you're serious about getting stronger and faster.