I assumed that when TLWR said she wanted to do something with the eggs, she meant selling them as hatching eggs, or selling the babies. By keeping with only the blues, silvers, blacks, and chocolates you're only working with 2 genes and various combinations of them (Blue dilution and brown dilution). If you add the fawn and white duck, you add dusky and runner pattern genes as well. And since you don't know if your other ducks (the blacks, blues, silvers, and chocolates) are pure for Mallard pattern, light/dark phase, runner pattern, bibbed gene, buff dilution, or recessive white (since their expression is covered up by the extended black gene) you could get some really complicated genetics going on if you mix in the fawn and white, especially since the extended black gene is dominant, covering up any of the above variations till the 2nd generation.
As far as getting interesting results from the silver duck: Silver (meaning extended black with double blue dilution.... not the other silver, which is dusky pattern harlequin phase), if you can get a double dose of brown dilution in there (or single in the female, since it's sex-linked) while still keeping the double blue dilution, you'd get a color called lavender, which from what I've heard is a difficult color to perfect, and you'd have to raise lots and lots of babies.
It's rather complicated, but if you used a chocolate drake and a silver duck, your first generation would be sex-linked, with the males being a regular blue, and the females being a brownish-blue. If you mixed these, 1/8 of their offspring would be the "lavender" color. The other 7/8 would be an assorted mix of silver, blue, black, chocolate, and brownish/blue. Some of the silvers, blues, and blacks would carry hidden brown dilution genes (chocolate genes), which may pop up in the next generation, so they can't be sold as pure colors.
If you don't have a lot of room, I'd stick to the silver, blue, and black, and not even mess with the chocolate or the fawn and white. That way you know what you're dealing with, and know what you'll get.
There are some very good genetics people on this site, and they can tell you lots more than I can, and I'm also sure they'll correct me if I'm wrong in what I've said above (that's my disclaimer.... I'm not an expert at this).
Unless of course you're looking for interesting colors and surprises, in which case you can forget all my ramblings above and have fun! And there's absolutely nothing wrong with that either. Personally I like the challange of trying to figure out this genetics stuff, and the challange of trying to get a true-breeding flock of an unusual color. But that takes time, patience, lots of room, and tons of duck food! (not to mention the mess, especially in the wintertime when it rains!)
Have fun!