You need to order the following:
50-0162 Medium Head Assembly (this includes the nozzle, the tip and the head, as well as the head washer)
50-046 Needle bearing (this is tiny and can get lost, better buy two!)
50-0602 Medium Needle (I suggest buying two, and while you're at it buy an extra Fine Needle 50-0401, bend one or dull the tip and you're pooched until the replacement comes).
I see no reason to buy another chuck, you only loosen this to remove the needle.
Regdab is recommended as a lube, and it also helps prevent dry tip problems if you spray acrylics. I bought the Iwata Super Medea Lube at the LHS and it's twice the price I've seen the Regdab online for.
That's a nice AB you've got on order. I have the 150 with Medium needle which is the same brush only as a siphon fed version. My plan (Shhh, don't tell the wife!) is to order the 100G with the Fine needle. The parts are interchangable.
Now all I need is a couple of quick change connections and I'm set!