I don't have any experience with flow through bins, so take this for what it is worth.

I think the idea is not to pocket feed a flow through bin. You always want to top feed. You want the bottom of the bin to be finished compost, which means that all new food and bedding will go on the top. I don't think you are going to feed enough at one time to cause the bin to heat up, unless you feed a lot of grains.

If all of the food goes on top, you will soon have a mucky mess unless it is either mixed or layered with bedding. Layering is less work.

The idea is that you wouldn't be waiting for the worms to eat all the foodstock before adding more. I had a garbage bin that I used like this and what I did was if I put in a heavier load of food then that would mean that I would have to put on a thicker layer of bedding.

You can pocket feed but it would depend on the amount. If I have just a small amount then dig and put in if you want. When watermelon season is here then after a batch I will put in a very thick layer of bedding.

If you process the foodstock greatly by liquifying then you have a higher chance of heating up. Just place the food in there specially if in large amounts in bigger pieces that way it will take longer to become fully active and thus lessening the chance of heating up too much.

As to wetting the bedding you will have to see as you go, with a flow through you will use many more times more bedding and that is what keeps the bin from heating up.

My father in law is currently building me a flow through bin and I cant wait as I see all this extra food that could go in there.

I throw scraps on top of my flow through. If it starts to smell a little, I throw some cardboard or shredded paper on top.

I don't bury anything. I don't chop anything. I don't freeze anything. I don't add water.

Everything breaks down fine, by the time I pull it out of the bottom.

You can start a hot compost bin if you add too much bedding and food at the same time. Put stuff in as you come across it.

I alternate between adding a layer of food and then a layer of shredded newspaper and lifting up the newspaper to add more food. If the bedding still looks basically intact, and the food under it is mostly gone, then I lift and add more food. I'll do that 2 or 3 times (I feed once or twice a week), and then when the bedding no longer covers the food well enough to keep the flying critters out, I'll add a layer of food and a new thick layer of bedding. I do freeze, but that's because Hawaii has LOTS of fruit flies. Other than that, I don't do anything to the food scraps in the way of preparing them. (I did cut up into about 1 inch cubes the sweet potatoes that were bad when I bought them :-(

I don't worry about heating since there's so much space down below where they can escape if needed. I only harvest when I need the stuff, so the lower layers are there for a long time.