How to prepare gnocchi dough for mixed ingredients? After reading a recent post on incorporating vegetables into gnocchi (and presumably of potato/flour based pastas), I tried my own mixture of veggies and it came out great.  

Here is where the consternation fits in - balancing the potato/vegetable:flour ratio to compensate for moisture while mixing. It took what seemed to be a lot longer than I thought it should, and I believe this was due to the moisture. Unfortunately, I do not have a stand mixer and hope someone can contribute a nice rule of thumb for dough and handmixing. 

I started with even 1:1 ratio of pureed veggies (moisture squeezed out) to russet potatoes. for the sake of illustration lets say that came to about 6 cups of mix, I began adding all-purpose flour by the 1/2 cup, gradually folding each in with a wooden spoon in a bowl. Around the 4 cups mark I pulled the mix out and put it down on the counter and started adding it more aggressively while kneading the dough by hand (it was still sitcky enough that it left quite a cleanup). All told I think there was about a 6:8 cup ratio of potato/veggie:flour before i could start cutting and forking the little guys.  


I know it's loosely based around how much and which veggies are added, but does that 6:8 sound about right?   
Although stirring in some of the flour before putting it on the counter (to stiffen the initial mixture) seems necessary, once it holds together is folding the flour in necessary?  
What options do I have for playing around with the types of flour to cut back on moisture and minimize the amount of flour needed? (particularly, would it be better to move away from all-purpose?)  
Does it really just take forever to mix this stuff by hand?
You're on the right track!  Start adding your flour in the bowl as you did and when you can remove it without it being too tacky then start working it on a cutting board or countertop as you continue adding more flour.  Sounds like maybe you pulled it out of the bowl too soon.

As for a specific ratio of flour to potatoes/veg. that's going to depend not only on the items you're using, but also cooking method (for instance I recommend baking potatoes for making gnocchi rather than boiling as they will be drier and need less flour added, thus making for a lighter dumpling).

Once you have enough flour in the mix so that you can knead it and work it, I usually do a "stretch" or "tug" test but holding the dough up in the air and with my hands at each end and then kind of pull and push the dough from the ends (hard to explain in text but imagine the push and pull of two magnets you're trying to push together).  If it has a bit of tug and a little elasticity you should be fine.  If it doesn't, then either knead it a bit more, adding flour only if it is sticky.  If it still doesn't have any tug after kneading more, then you probably don't have enough flour.  The gluten in the flour is what's going to help hold it all together so that you don't just end up with disintegrating mashed potato/vegetable blobs in your poaching water.  If you're making a big batch it will probably take longer than you expect to get it to the right consistency.

As for types of flour, the more protein a flour contains the more liquid it can absorb.  While I have not made gnocchi with bread flour, it would take less bread flour than all-purpose to absorb the moisture in the mix.  It will also have a more distinct flavor from the add'l protein.  One caveat is that it could end up making them too tough due to the extra gluten.