I took what George Collier wrote and tweaked it. Not to say his is bad or anything. Its just mine is different, and maybe it will help. Done tones of sheet film this way for years with nary a problem with scratches and never any uneven development.
Unload from holders into a film box (I turn the box to the horizontal orientation, and the film perpendicular to that, so the edge hangs over the side. Makes it easy to grab later), e-up, putting all the film in the same orientation, with the code notches in the lower left except the last sheet, which you put with the notch in the upper right and still e-up, so I can find it in the dark.
Hold films in the left hand. The code notch that is in the upper right will be your first sheet to go in, and the first sheet to go out. It is your orientation sheet.
Pull films out with the right hand (I fan them out myself, but I've very used to doing sheet film and it might take you a while to get used to doing that), one at a time, drop into a tray of water, E-UP (never, I repeat NEVER put film e-down. IMO there are too many things at the bottom of a tray or the sides that can scratch the emulsion), the same temp as the developer, pushing down into the water with the little finger, keeping the rest of the hand dry. Go through the stack, herding them all together as you go.
Now, pull the bottom one out, just not at too sharp of an angle or you can get a scratch, and lay it on top, pressing in down in the water gently. Repeat this through the stack at least 2 times. I usually go for about 3 minutes of pre-soak for sheet film just to make sure it is wet all over. Keep feeling that upper right corner for the code notched sheet. When you've gone through the stack at least 2 times, and you come upon it, stop...that is your first sheet and you will want to begin the transfer to the dev.
Pull out the stack and drain for only a second or two.
Place them, E-UP, into the developer and begin shuffling, bottom to top. Rotate 90 degrees clockwise every 1/5th of the development time. (Divide the dev time by 5 i.e. 10 minutes/5=2 minutes. So rotate the tray, or the stack, 90 degrees every 2 minutes. That way you will return to the proper orientation when it is time to put the film into the stop).
Agitate constantly the whole time.
When your dev. time is up, pull one sheet out at a time and place in the stop bath. Do this by keeping one hand in the dev, which you will use to grab the bottom sheet and hand to your other hand, which will put it in the stop. Taking the whole stack out at one time gives the last sheets less dev. than the first sheets, since you put in one at a time. Call me picky, but I like to give all my film the exact same dev. time.
Dev. is pretty cheap, considering and if you have more than 1 run to do, having quite a lot of dev. won't hurt and will allow 2 runs to go through without having to replenish. Per kodak's data sheet on D-76, you can get 16 8x10 sheets out of a gallon of D-76 straight. That would be 64 4x5 sheets.
http://www.kodak.com/global/en/professional/support/techPubs/j78/j78.jhtml#004
About the dust - Lee's suggestion about the camera is a good start. What I do every once in a while, is take off the front lens board and the rear glass, extend the bellows as far as possible, and wipe the inside with a damp cloth. But more importantly, when loading the film, after the film is inserted into the holder, I blow off the surface with air. Then close the slide. Since dust is most likely falling on your film as you load the previous sheet, and hence staying there when you load it, dusting it off just before closing the slide will eliminate 99% of your dust. Guaranteed.
Maybe I'll make a little video on film development and post it since it is hard to describe the process and easier to see how its done. Give me a week or so.
Hope this helps.