1. What's the endgame? You see, I'm not really looking to make exercise and fitness consume my life. I would kind of like to minimize the amount of time each week that I would need to spend maintaining my body. I'm not looking to get super strong or swole, just something that's healthy. So if I start training and getting stronger, when do I say "this is enough" and more importantly, what happens then? I'm afraid of getting sucked into more and more complicated and more and more time-consuming exercises as my body gets stronger. Like I said, I don't want to make this my life. I just want to maintain a modest level of fitness to improve my overall health and wellness. So I'm interested to know what happens after one gets past the initial strength building and settles into something sustainable.
You don't have to complicate your routine or spend more time. For example, I weight train about 3 days a week for about 60 minutes each time. I get stronger by maintaining a consistent diet and by doing the same few lifts (mostly deadlift, bench press, squat, and overhead press plus a few small accessory lifts) week in and week out. The only changes I make is to increase the weight I lift from time-to-time. That's it! Nothing more complex, nothing more time-consuming. If I ever got to a point where I feel I am 100% satisfied with my current strength, I will simply stop increasing the weight and stick to maintaining what I already have - again, nothing complex.
2. What are the long-term consequences to embarking on these strength building exercises? Like I said, I'm in this for health, so I'm not looking to cause more problems for my body for the sake of getting stronger. I don't care about strength or body shape for its own sake. I just want to be healthy. I'm interested in strength because I want to maintain my ability to be active as I age as well as gain some of the other health benefits that strength brings. But I am a little concerned about causing injuries and aches, especially those that might only show as I get older. Since I'm planning to be in this for the long haul, I'm not in any rush to reach some target so I'm okay with taking it slow to reduce the chance of damaging my body. What I'm afraid of is irreversibly damaging my body in some way before I know what I'm doing and then regretting it later. What are the main things that I have to watch out for and what should I be doing to minimize this risk?
The risk of injury short-term exists with any training routine - even just glidingn on an elliptical. With that said, if you begin any routine, you should spend time first learning how to engage in the activity properly. Watch videos, talk to people on here, record yourself and share the video so we can point out issues with your form, etc.
Long-term, you will be in better shape if you stick to a weight training routine than if you do not, assuming you practice proper form. Weight-bearing exercises such as the squat improve bone density (osteoporosis and associated fractures are a huge problem in older individuals) which is hugely advantageous as you age. Building muscles in your legs is beneficial for your knees; more muscle helps to stabilize the area in and around the knee, which helps to reduce chances of you having knee pain as you age. Strengthening your back and core (again, can be accomplished with squats alone) will improve your posture, whether sitting or standing, which will reduce the risk of back injury as you age.
Personally, I think keeping body fat low and having a decent level of muscle (you don't have to Hulk out) is the key to healthy aging. I would highly encourage you to look into a basic lifting routine such as Starting Strength. I want to reemphasize that proper form is the key to success not only with weight training, but even with your day-to-day life. For example, don't roll your back as you bend over to pick something up, squat down and pick it up using your legs and a straight spine.