30% of important parts took place in malfoy manor

I'm not sure Dumbledore took everything for granted, but he had to be careful what he shared. Truth is indeed that Dumbledore may have counted too much on Harry (and Hermione) to riddle things out. It is not exactly clear to me if Dumbledore actually knew Bellatrix had the cup. Bellatrix unwittingly gave that away when she was struck by fear when the Sword of Gryffindor was found in Harry's possession, which was supposed to be stored in the same vault as the cup (Bellatrix didn't know the sword in the vault was a fake). Of course, maybe Bellatrix also didn't know that the Sword would always present itself to a true Gryffindor who needed it (if they had the sorting hat, which was NOT stored in that vault) and I don't think any protection in Gringotts could have stopped the sword from doing that. I am also not sure Dumbledore knew the tiara was stored in Hogwarts all the time.
Of course, the clues Dumbledore left Harry was too vague at best, but it's not clear what Dumbledore knew and what he didn't. And the taboo (which was Harry's 'betrayal') was only put on Voldemort's name after Dumbledore died....

what i mean is that harry had barely scraped the task given too him... he could've died when he was at the ministry or gringotts or when he dived for the sword or at godric's hollow , even though they are relatively tame, what really bewilders me is the malfoy mayor encounter. even though it was harry's fault, and dumbledore couldnt have known that there was a horcrux in bellatrix's vault, harry had a close shave being transfigured, hermione was almost killed (pretty sure they couldnt have done anything without her), and they had another close shave trying to escape, i mean what are the odds? and if they hadnt gone there, harry might not have known about bellatrix's secret, and wouldnt have gotten draco's wand and not being the rightful master of the elder wand. omg, almost 30% of important parts took place there. so, if they hadnt gone there, the story wouldnt end as it did