Putting in a kit in a competition 750 and have a few qualestions

First. How do I ensure the mixture circuit is clean ?
I've removed the screws and cleaned that passage out but how to I ensure the passage supplying fuel to the screw is clear ? I can't seem to find the supply

Second - I assume these are stepped needles? I've seen diagrams but never seen one in person ( see pic )

Lastly the passenger side primary jet was in the hole but not screwed in. Looks like it vibrated loose. looking at the jets the primary are .098 and the secondary are .096.
To my simple brain this seems backwards. Since one loosened up I'm thinking someone went through the carb once before - could they be backwards ?

The carb sat for several years with fuel in it. Many passages were plugged. When it would idle I could put my hand over the top of the carb and the engine would clear up and idle better. I checked for vac leaks and found none. After looking the he carb it was clear there was a lot of passages hindering fuel flow.