Let me answer you the way a good IT manager should:
1) Newest version? So what. This isn't a game and it isn't a race. We're not here to play with the newest toys.
2) Standards? So what? What do they give me, the organization?
3) Name those issues. If they are issues that affect our daily work routine, or are critical security risks, we should upgrade. Otherwise? What's the use?
4+5) Wait, you said that building new web apps for IE6 and IE8 costs more money, but then you say that IE8 can run IE6-compatible sites, right? Great. We'll build IE6-compatible sites and have them work with IE8 as well. Win-win!
Remember that there's no such thing as a universally better browser. An organization has to choose the tools it needs for the problems it has and the tasks it has, not because they're prettier, or run javascript faster, or are open-source.