Re: how did the glaciers move uphill?

You're operating under the assumption that the glaciation came only from the
North Pole, but this is not the case.  The initiation of the glaciation was 
most probably a continental phenomenon, and it more or less "began" over a 
huge area of what is today eastern Canada (roughly from northwest Alberta 
over to northern Quebec).  Another source of ice was glaciers spilling 
eastwards out of the Rocky Mountains.  Many introductory texts in geology 
will have some maps showing the general spread of glaciation; the
particular one I consulted was Press and Siever, "Earth" (pg 379).

One theory of how the glaciers grew was that the winter snowpack was so 
thick that it never melted away during the summer, over a very large area. 
Thus year by year it built up and eventually the ice became thick enough 
that it began to flow due to the enormous pressure making the base of the
ice rather plastic.  This ice sheet then spread out from central Canada
eastwards to Labrador and the Atlantic, north into the Yukon and the Arctic,
westwards to collide with the Rocky Mountain glaciers, and southwards into
what is now the northeastern part of the United States (incl. Minnesota). 

Note also that the glaciers were well over a mile thick (i.e. in excess of 
5,280 feet) and such a monstrous glacier could very easily ride over and 
"submerge" a 500-foot elevation difference.  Consider that they gouged out 
the beds of the Great Lakes, and then came back up from those depressions to 
advance much further south.