First, some context: I'm a 32 years old developer who spends most of the day sit, go to swimming classes once a week, and does weightlifting (at home) whenever it finds time, now moving from Stronglifts to Starting Strength (but sadly not dedicating the three times a week they recommend, so I'm not doing heavy lifting yet).
From my swimming classes and paying attention to squat videos, I have realized that I lack (a lot of) flexibility in:
Now the questions:
1) Should I be concerned about this issue? Let's say, it's going to affect me badly when I become old.
2) If I should, then should I spend all time I have doing flexibility exercises, or can I mix them with regular strength exercises? (squat, bench press and pull ups are the ones I like the most)