I believe weight training is excellent exercise.
It is especially good if you want to develope the strength and size of your muscles
Yes but also to maintain muscle mass when you age, however I find it kind of boring.
It is a bit boring weight training uses a variety of certain muscle groups together to help build the muscle up
Yes, and I believe it works better if you take protein supplements.
Many professional and non professional sports use weight training for their players, like Football, baseball, and even track and field
Yes, I am a recreational runner and weight training is recommended to avoid injury and improve performance, but it is difficult for me to do it anyway.
You could try the weighted clothing available, you just wear it, and you dont have to do an actual work out
Sounds easy but also like a gimmick I doubt it would be the same or would have any effect at all,  I remember those reebock that were suppose to exercise you by being unbalanced or something, I believe they were proven not to work.
the weighted clothing is a form of resistance training, they do work, when you take them off you feel light as a feather and has been proven to really help runners