This is very hard to answer, and since you never tried the hobby pre-paleo there is really no point of reference.
1: You tried the sport of road cycling and discovered it is fun. That probably would have happened regardless, but your paleo leanings help you realize that you are exploring the world. Paleo is synonymous with thinking differently than most and going out and doing "new" things so it makes sense that you would like it. I would bet your mindset from paleo helps you think about it more like having fun than "oh man time to get this workout in"
2: The rapid progress is going to happen for any beginner, though one year in who knows if you're really a beginner still. Perhaps you are weight training too, or workout out smarter than a non-paleo would. I'd imagine that paleo foods, being highly nutritious, would help anyone make faster gains. In addition to the nutrition, most paleo-minded people like to work smarter (even if working harder) so perhaps you are doing better workouts than a long, slow, endurance racer eating breads and pasta.
3: Goals are meant to change. When you reach a goal it just means that you have the opportunity to make a new one. It's good that you have put effort in and achieved things you didn't know were possible for you! You have nowhere to go but anywhere you want. If you're interested in putting goals on paper make sure to have short-term (weekly/monthly) medium (three months) and long term (1-5 years.)
Congratulations on eating well and doing something you love! I believe your enjoyment of your activity is two-fold. Certainly better nutrition is helpful, but the paleo-mindset of trying new things and being adventurous is great too and is probably part of it. Better to go cycling for fun than to try and burn off donuts :)
Personally, I started Crossfit and Paleo shortly afterwards and I noticed huge improvements in my abilities. That lead me to heavier lifting and on to CrossfitFootball's programming. I love it and I'm glad that I can eat well and keep on adventuring!