I downloaded the upgrade patch using Pix's Ultima Patcher,but I had two problems:
I like to listen to my own music while playing, is there a way to keep the graphics without adding the music? Just turning it down in the audio mixer would also get rid of the game-play SFX like the poison sound. Also, is there a way to use normal graphic ONLY for the invisible wall tile? the new tile-set makes it very hard to spot the fake walls.

DOSBox has a MIXER command for separately adjusting sound vs midi volume, does that work?

You can also use xu4 (just search for "xu4 Ultima IV" in Google) to execute the game, which gives you all sorts of options, like disabling the music but allowing for Sound FX. I've attached a screenshot of what the xu4 GUI Configuration GUI looks like.

It also gives you the ability to switch between different visual looks in the Video options under the "Graphics Scheme" section.

Alternatively, as pocococo stated, you may edit sound settings via dosbox by editing your "dosboxULTIMA4.conf" file in your Ultima 4 install directory (mine is located at D:\Games\GOG Games\Ultima 4 - Quest of the Avatar). You can do things like change "nosound=true" to enable silent mode