Ghaz is a blast to play, and he is a lot of points. I personally like playing him when I can regardless of what experts have to say.
10x boys squads will get mowed down and fail morale immediately. I'd recommend going with one unit of 30, and 2x10 grots to fill out a battalion.
Tankbustas are great, but cut it down to 8-10 and put them and 2 bomb squigs in a trukk. It's open-topped so you can still cruise around and shoot with some extra protection.
I'm assuming filling up the the Battlwagon with MegaNobz, Ghaz, Painboy and Nob w/ Banner? That is a serious convoy but I'm not sure you get enough from the Waaagh banner. I've used one and I never get enough out of it to justify it.
If you can find Mek Guns cheap, swap them out for Deff Dreds. Traktors, Smasha's and Kustom Mega-Blasters are all better use of points than the Dred's, and they are fun to play becuase they won't die immediately. Trust me on this one.
I generally don't run any boyz squads, but I will have 1-2 Kommando squads to counter-attack or seize objectives.
Hope that helps and good luck.