Classic case of woulda, shoulda, coulda. As far as The Beatles feeling responsible for the deaths of Pete Ham and Tom Evans, they shouldn't. Not in the slightest. Just about anybody who commits suicide is gonna do it eventually anyway. If it's not over one thing, it will be over another.
As far as Pete Best, I agree that he deserves the royalties from Anthology. And I'm glad he got it. But I don't think The Beatles should have felt any obligation to "hook him up" earlier. The dude was kicked out of the band. He and Paul didn't even get along. While I think MAYBE out of good nature, they should have given him a little something, they certainly shouldn't have felt obligated to do so.