a word on work experience: it really isn't discussed well enough in context of what b-schools are looking for, but most would certainly agree that it's the quality, not the quantity, of the work that you do that will make a difference in b-school admission. If you're able to show continuous progression and leadership/managerial ability, even with just 2 years of experience, you'll be well ahead of most of the other aspirants with 4 or 5 years of WE. However, having said that, most people will not be able to fully develop their "progression and leadership ability" within just 2 years of time, which is why most b-school has an average WE of 4 or 5 years.
In terms of GMAT, GMAC has already published that in 2012 there's going to be a new format to the GMAT, with "integrated reasoning" (I think that's what it's called). If you need to retake when you're applying due to a lower score at a top school, you'd be looking at a different GMAT from what you would experience today. There's really no telling of how schools are going to view the scores from pre-change and post-change. I'm sure that if you scored a 750+ today, your score would still be on the top of the top after the change. I don't think any business schools are going to shed light on this just yet, since the change hasn't taken place yet. Without a good sample size of students taking the new test, it's hard to determine what the percentiles may be. For example, a 90% percentile right now pretty much translates into a 700. With the new test, the 90 percentile may well be just a 650, or 740, in which case it'll be hard to justify what your 700 is from today.