To me it means only pick fights that you have a chance of winning. You don't learn to fight better by getting yourself killed.

I think it rather implies you should fight smarter.

Arguing with people that will only get more entrenched in their oppinion the more the argument goes is couter productive no matter how right you are. So if you need to learn that, by all means, argue with those poeple untill you get it. But afterwards, learn when to save your breath.

No, it assumes you have finite resources and finite bridges to burn, and advises that you do the resource and bridge allocation wisely.