Sometimes if you walk to a previous stop or come in from a different line you can find a seat more easily. If it makes sense you could even go a couple stops "backwards" if the train reverses at that point. Shifting your schedule might be another option. At one phase I took standing as a challenge and drastically improved my balance over a couple of years, though it's not fun when the car is really crowded.
Sure, but at this point we are just hacking the system. Which is fine, I guess, no harm is done, but it feels wrong :)
Honestly this is one of the undersold advantages of public transit. It can be fun to optimize your path and switch things up both on a macro and micro timescale. In a car since I'm constantly aware of what I'm doing, taking a less efficient path feels like I'm wasting a part of my life. Taking a less efficient path on public transit feels like I'm taking more time to stop and appreciate my surroundings. Especially because sometimes that alternate path gives me a better view.
A coworker once told me his view of his commute drastically changed when he realized he could take the ferry to work. He got fresh air, it was less cramped, and it only took an extra 5-10 minutes.