Riding is great no matter what your age is! Here are my answers to the posted questions:
I'm 52, and I ride a skinny-tired road bike, a Bike Friday Pocket Rocket, and one of two touring bikes in my bike stable - a Bike Friday Air Glide, and a "big-wheeled" touring bike custom made by Peter Mooney.
On the vitamins/minerals front, I keep things pretty simple with a multi-vitamin and extra calcium.
On the whole, I don't think my age has slowed me down at all. This year my mileage is extremely low - only 1200 miles so far - because of an
unfortunate crash back in May that pretty much curtailed my cycling. I'm riding, but only short distances, and I actually had to cancel 3 tours that I had planned for this year. I'm dreaming of next year for touring, and in the meantime I'm on my bike on the weekends and getting other types of exercise during the week.
I really like touring by bike. I initially started touring with touring companies (way back in 1989), and in 1998 I switched to solo tours carrying all of my own gear, and I have to say that I really prefer touring on my own. If you're interested, you can read about my solo tours at
denisegoldberg.crazyguyonabike.com. And in a normal year, I also commute to work by bike, but I'm a fair weather commuter during the well-lit months - which typically runs from May to September.