Here are the answers.

1. Film used to be both glossy and matte. The matte was often on the back. It helped with retouching, but interfered with scanning. So, the matte was removed to facilitate scans and allow retouching in PS (<- gasp). However, gelatin is naturally rather glossy. The matte has to be added, and should not interfere with grain.

2. T-grains lie flat naturally due to the settling or packing process as the gelatin dries. However, the gelatin must be flexible enough for the film to turn corners in MF cameras so that the gelatin does not crack and the t-grains do not crack. Either one can hurt the film image badly.