Regarding the solid mass in fermenters, I think the thought there is that hop compounds can stick to anything in suspension, which would then pull them out of solution during fermentation/conditioning. It's a reasonable idea, but I'm not sure just how much effect this has in the end. It certainly can't hurt to take some extra precautions, but I'm not personally going out of the way to do this.
Keeping the dry hops in suspension isn't really feasible for the homebrewer unless you ferment in a conical or closed keg where you can blow CO2 through the beer to rouse the dry hops. But, as mentioned before, the vessels we typically ferment in as homebrewers leave more surface area for contact with the hops.
My main tip for IPA's is to use more hops.
That will generally overcome any of the issues mentioned.