1) Given such tidal forces how did the moon accrete in the first place?

Although those tidal forces sound impressive, the Moon nonetheless formed outside of the Roche limit - the point where tidal forces are stronger than the self-attraction of a body, so it wouldn't have been torn apart - it would have followed the lower energy path of collapsing together into a ball, in orbit. that ball might have been deformed, might have been rotating rapidly, but would rapidly spin down under the influence of those giant tides, remaining molten while it did so...

2) is it possible that the impact that formed the moon and the subsequent tidal action is responsible for the the amount of heavier elements that are accessible to us in our crust?

A philosophical question. One that I have tried to answer myself in the past with limited success. Let's look at the issues:-

Why do we have heavier elements present in our crust?

Well, actually, we don't. Things like platinum, rhodium, rhenium etc are dashed rare. Rarer in the crust than in average solar system material. They are concentrated in the metallic core of the earth, (and in iron meteorites which are fragments of the disrupted cores of differentiated asteroids).

These elements are generaly labelled as "Siderophile" (literally Iron-loving). These have affinities are concentrated in iron-rich melts. In the early earth, it is beleived that Iron and Nickel melts sank to the core, taking with them other siderophileelements and depleting the mantle and crust.

Chalcophile elements are those compatible with sulphide-rich melts - these include As, Zn, Ag, Pb etc. Again, these tend not to be concentrated in the crust.

What we do have a good concentration of are "lithophile" elements, which bond readily with normal rock-forming minerals. These are concentrated in the Mantle and Crust.

So where do we get ore minerals from?

Plate tectonics is an important part of the answer. Over geologic time, mantle material has been swept through repeated cycles of partial melt - crystallisation of basalts, hydrothermal alteration, subduction and remelting. The product of this is "granite" - enriched in luthophile and incompatible elements, and the last stages of granite crystallisation and hydrothermal circulation produce ore deposits around enriched granite bodies. Tin, copper, silver, Lead-Zinc, Mercury etc...

Billions of years of recycling of the mantle and of small amaounts of crustal material, and the same billions of years of high and low temperature water-washing of the crust has concentrated the most incompatible minerals into ore pockets. Biological activity and sedimentary sorting through density, hardness etc. also concentrate some minerals and their vital elements. Oh and varying redox conditions do funny things to some elements and make them behave differently.

So, we're getting a bit lost in the details here but basically, Earth has ores because Earth recycles its crust and Mantle. Mars doesn't do this except in very limited circumstances at the base of the giant volcanoes where early basalts got remelted to crude granites. Venus doesn't do this very well. Mercury and the Moon don't do this.

if you can argue that the Moon-forming impact caused plate tectonics to work in a differrent way on Earth than it would have otherwise, then you have your cause and effect. I tried that argument but couldn't sustain it scientifically...

For further reading, google "+chalcophile +lithophile +goldschmidt

http://geology.about.com/gi/dynamic/offsite.htm?zi=1/XJ&sdn=geology&zu=http%3A%2F%2Fwww.science.uwaterloo.ca%2Fearth%2Fwaton%2F5a.html