There is one common law school case where a court smacked down Henry Ford for saying he didn't care about shareholders, just his workers, but that's because it was the Dodge brothers bringing suit and Henry Ford was being a huge dick. That case wasn't really a correct statement of the law even at the time.
That depends on what you mean by "no-holds-barred". If the company is giving up potential income they had better be able to explain the reason, otherwise it is a breach of fiduciary duty. Of course they're not allowed to do anything illegal, and you can probably get away with saying "this would give us bad PR". But "we don't enforce our patents because we think patents are stupid" is definitely a breach of fiduciary duty.
See here:
http://www.litigationandtrial.com/2010/09/articles/series/sp...
The only reason eBay v Newmark exists as a case is that the managers are also the majority shareholders, which introduces a conflict of interest. (Well, that and the fact that eBay are dicks who were trying to fuck with a key competitor.) It's a weird case, and that decision has no practical implication for Bezos.
That bit from the decision comes up in regards to complicated stock shenanigans designed to keep eBay from getting more CL stock. The principle isn't being applied to ordinary management decisions, just decisions about stock ownership and board seats. So even if this decision did mean something for Bezos, it wouldn't mean anything about him deciding not to enforce patents.
Even that doesn't pin them down. Amazon can easily say they believe it is in their own long term interests to campaign against patent laws and therefore sacrificing a small short term profit from the one-click patent is a logically correct way to maximize long term shareholder value. The argument that a company "has to do evil thing X" to maximize shareholder value is pretty much always just an excuse for avoiding argument about whether "thing X" is evil or not.
http://www.litigationandtrial.com/2010/09/articles/series/sp...
If on the other hand a company's charter stats that 50% of all profits are donated to charity before it goes public then you your unlikely to successively sue them for continuing to do so.
http://www.nytimes.com/2005/01/11/technology/11soft.html
Along massive quantities of data. http://depth-first.com/articles/2011/12/15/ibm-donates-large...
Nope, as far as I am aware there is no law that companies must maximize the value for their owners at the cost of all other considerations. This gets brought up constantly, and I've yet to see anyone support the claim with evidence. Sure, you can sue for breach of fiduciary duty, but that duty does not include no-holds-barred maximization.