I do not know about Misha on faster surfaces. If you mean "grass" as a faster surface than I agree, because in terms of groundstrokes grass is even slower than clay. But for "really" fast surfaces - with fast and normal (or high ) bounce - his singlehander will probably be a liability - not enough time for backswing.. Single-handed topspin backhands are vulnerable indoors and on fast hardcourts...
As to playing Argentina.. Top-form Safin will blow away anyone on clay, except for, probably, Kuerten, and he is not Argentinian..
. Whether he'll be in good form by then, and whether we would get the third point remains to be seen. I wonder, given Nalbandyan heroics at Wimbledon and very good abilities of Canas on grass, wouldn't Argentina build a grasscourt for that..
But basically, if Canas is at his best Argies can really challenge us even if we are at our best - other Argentinian players - I do not consider them world-class as of now..