The message is a status report from the X server, and it is usually safe to ignore it. At the present time utah-glx does not fully support nVidia cards, so features such as DMA are not used, and the performance is limited. You should be using nVidia's own binary XFree86 4.0 driver instead. There should be an impressive performance increase. This is a bug caused by the use of paletted textures.
Most MODs are compatible.
Check the page on the OpenUT website for the latest information. First, you need to download the Bonus Pack. This is due to a known issue with the sound samples. You should ensure that you are using 428a or better in order to avoid this problem. It depends what you mean, really.