I don't put that much thought into it. I just dump the ground up food into the bin. They can process our kitchen waste much more quickly when it's already broken down by the processor.
That is what I did too. Then I took the ground up food and put clumps on newspaper lined cookie sheets. Put in freezer, then, when frozen, tore each hunk off (newspaper and all) and stored in a plastic bag. I can take out what I need and the piece o…
Do what Laurel says, and:
Add nematodes to your bin--they feast on fruit fly larvae.
Stop adding any citrus peels--bananas, oranges, etc. Fruit fly eggs in the peels. This regimen has eradicated the fruit fly issue for us.
When you open up the bottom, the material down there is usually pretty compacted, so it actually requires squeezing and/or hitting the outside of the bag to dislodge. It depends on how long you wait to harvest it and how moist things are, but it generally does not spill out in great quantities. Usually I am wishing the compost would come out quicker than it actually does. Happy composting!