Rohl's chrnonology has been discussed elsewhere. It has serious problems in dealing with Assyrian history and the main evidences Rohl uses can be adequately explained within the conventional framework.
In reading about Kahun some questions are raised. The Hebrews were supposedly enslaved, yet according to this page there is evidence that workers at Kahun went on strike
Kahun, Middle Kingdom Workers
Other reports indicate that there were numerous foreigners in the town, including Europeans and Hittites. So interpeting the abandonment of the town simply as the inhabitants heading off as the Exodus is hardly adequate.
Petrie reports that the buried babies were often "some months old", and not newborns as the Bible would have us believe, if the children were Israelite. I see no evidence in Petries reports that the burials of babies were associated with foreigners or that their parents were impoverished or slaves.
Petrie also reports finding pits within houses at Medinet Gurob, where personal posessions had been placed, burnt and buried. But this - although similar to the reports of buried babies - is associated with Europeans, not Asiatics by Petrie.
(Petries reports may be found here
http://www.kahun.man.ac.uk/excavations.htm )
The Leiden Papyrus is also questionable as evidence. It is not known what period it refers to (my understanding is that it is usually taken as referring to the First Intermediate period). The Second Intermediate period is also dodgy as evidence since it is a period when Asiatics came to dominate Northern Egypt - including the Delta area where the Israelites were supposed to have been settled.
Finally your reference the the Flood story is way outside of archaeology. Archaeology finds no sign of a worldwide Flood, local Flood stories don't include Egypt, and also even remians of pre-Dynastic Egypt, significantly predating the Pyramids of Gizeh.
e.g
http://www.library.cornell.edu/colldev/mideast/predns.htm
Egypt had at least a partly agricultural economy as early as 5000 B.C., and archaeologists have uncovered royal tombs dating back as far as 4000 B.C.
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