Okay, I pulled out the booklet. I will say this, buy it if you have any interest as it does cover most of what you seek. Some summation to your questions:
Sword Brethren, Serving Brothers – Called Diener, and they were the equivalent to sergeants in other orders. Wore a black, brown, or other dark color surcoat/tunic. Shield was white with the order insignia.
Other units/forces would include Polish Knights, German foot crossbowmen (also in the Diener), German archers, German heavy cavalry, men at arms, German armored infantry, and German Knights. All of these are covered in the booklet in terms of how they were armed and what they wore to the point where I do not want to restate it all here.
Here is their order of battle at Saule:
Sword Brethren – Knights – 55
Diener/Nutbruder/Gastritter – medium and light cavalry, and infantry crossbow/Crusader cavalry/Guest Knights cavalry – 600
Germans (must be foot) – 600
Russians – 200
Livonians, Letts, & Ests – 1500
There is also and arms and armor section for the battle. Both sides are covered in decent detail.
The shield art I shared previously seems to be the one mostly used by the Sword Brethren.
I hope that helps. As I stated, buy the booklet as it has a wealth of info.
Buckeye Six Actual