With the brick wall texture, what format are you using? The transparency seems texture-based, so it is most likely something wrong with the texture itself. Bring the image in photoshop and check for an alpha channel. if there is one, delete it and export again.
If this is in a baked scene, edit the image output settings to disable the automatic creation of alpha channels in baked textures.
The problem wiith the tree can be solved by using multi-sampled alpha. This kind of artifact usually happens when one transparent object intersects with another.
Code:
import viz
viz.setMultiSample(4)
#higher values increase quality but decrease framerate.
#usually set between 2 and 16
viz.go()
tranModel = viz.add('model.IVE') #add a model, call it tranModel
GL_SAMPLE_ALPHA_TO_COVERAGE_ARB = 0x809E
transModel.disable(viz.BLEND)
transModel.enable(GL_SAMPLE_ALPHA_TO_COVERAGE_ARB)
viz.clearcolor(viz.GRAY)