1. I'm coming up on 62. I've pretty much always had a bike, but some of them were a little on the marginal side. Currently I have five to pick from I don't know the exact year of any of them:
A Klein Quantum Race, it's the last year for the Chahalis factory.
A Santana Noventa tandem.
A Bridgestone RB2, but none of the original components remain. My vision for it is a low maintanance road bike with bar end shifters and punctureproof tires.
The short trip beater is a Marin Bear Valley SE. It doesn't have any original components either.
My mountain bike is a Porsche FS. I haven't mountain biked in over a year. I still like the bike because nobody else has one like it.
2. I don't feel like I do anything special. I don't smoke or drink and I take an 81mg aspirin every day.
3. I ride prety much the speed that I've always ridden, but that's not all that fast. I'll generally average around 14mph for a 30 to 50 mile ride.
4. (see 1.)
5&6. At various times in the past, I've done lots of different things including mountain biking and commuting to work. Today I seldom do anything but casual or social rides. For all of the talking about bicycling that I do, I estimate that I only ride around 2,000 to 3,000 miles per year. I don't bother to keep track of my mileage.
7. Last fall my wife and I joined a gym and took spinning classes 3 times per week through the winter. It has proven to be one of the better decisions that we've ever made.
You didn't ask but, what's the big deal about being 50 or 60 or whatever? If I had answered the same battery of questions 20 years ago, I don't think that any of my answers, aside from what bikes I owned, would have significantly changed. That's what's real. To me, the biggest barrier that I face today is the unreal perceptions that people seem to have about what a fellow my age should be like. It affects me everyday in things like job availability, health care insurance availability and even what bikes the kid in the bike store is willing to show me.