I haven't yet finished my wood burning UDS,however I am a Stickburner and blend, as you call it ,my woods.
Depending on the meat I am doing, I start with a wood that will compliment the food I am doing. Then I'll layer another type the next addition of fuel.Then I will sometimes use only one type of wood through-out the cook.
In other words, if I'm doing Chicken, I rather like a Maple smoke flavor the total cook.
When doing Ribs ,my favorite is Cherry...totally!
Pork I start with a good Apple and finish with Hickory or Maple.
Beef is always(IMHO) best with Hickory or when possible,start with Mesquite and go to Maple to mellow the flavor.
As for the size of wood, in my Tejas2040CC, I use 8"Xappox. 3" pieces,starting with a "small-hot" fire to create a good bed of embers.
You could pre-burn chunks to start in a different container(like a chimmney) and add a smallish chunk about 4"X4", when needed.It is a good idea to keep the fuel chunks hot or warmed.
In a UDS, one could place a couple of chunks to the side of the bottom of the drum. This helps in ignition when placed in the fire basket.
Hope this helps and post a pic of your UDS, I have a design that will make stoking a stickburning UDS much easier, and without losing all your heat when opening the lid to re-fuel.
Have fun and,
Smoke Happy:)-
Stan aka bbqfans aka Old School