That's gonna be a tough tie for France, they probably would have been favourite at home . Gasquet's probably gonna beat Blake, but I'd still favour Roddick over him. The Bryans are also favourites but not overwhelmingly against Clement/Llodra. As for Tsonga's matchs it's tough to predict, since I have no idea if he'll be able to keep up his form. All in all I think we're gonna lose 3-2 as always...
Yeah I'd probably make USA favourites 55-45. As you say, the Bryans wouldn't be overwhelming favourites, but they should be able to exploit Clement as the weak link.
As for singles, I think it is "realistic" to suggest that Blake and Roddick can win a rubber, each...although it is tough to pick, with any confidence, which of the Frenchies they'd beat.