Dry hop facts and theories

Some things we know about dry hopping:

-Hop oils stick to yeast, so you want the beer to be as yeast free as possible
-Increased temperature means increased rate of extraction
-Many breweries bubble CO2 through their tanks from the bottom to rouse the hops up
-A lot of double IPAs call for multiple rounds of dry hopping

Some questions I have:

-Is it advisable to rouse the hops in our dry hop vessel? How often? Is the only risk oxidation and contamination? What if I purge the headspace with CO2?
-What's the benefit of multiple dry hop additions? If I add 2oz once, versus 1oz one day and 1oz another day, there's got to be a cross over point where they taste the same, right?
-What are some realistic time limits for grassiness? It seems like most people don't experience significant grassiness that they describe as a negative flavor until they dry hop for more than 14 days above 70*. Some people will say less, and some will report a month dry hopping is fine but 14 is probably average.

I love theories and discussions.

Agreed with your initial assertions.

I don't think rousing is worth it on the homebrew scale unless you have a conical. With a flat bottomed fermenter the hops are still pretty well exposed to the beer even if they sink. If anything I have to put by dry hops in a bag with marbles to make sure they are submerged.

I’ve settled on doing one round of dry hopping at room temperature for 7-14 days followed by keg hopping as the beer force carbonated at serving temp. The initial round of dry hops provide the bulk of the hop aromatics, while the keg hops ensure that the aroma won’t fade over a month or two.

For grassiness I think it has to do with the form the hops are in. Even with several months on whole hops I haven't had any issues. I've never left pellets that long, but it seems that everyone who reports the issue are using them. Pellets are broken up so the chlorophyll is more exposed to the beer.