You can certainly drive yourself to the venue but cannot guarantee parking. There are two parking lots on site but this could fill up quickly so try to arrive early if you are driving!
Colorado is known for unpredictable temperatures this time of the year but is not usually very cold. The Fall foliage and color change is usually prime this time of year. The ceremony and reception will both be held outside so a jacket is recommended for the evening once the temperatures drop after sunset.
We have a hotel block at at the Courtyard Denver South hotel. This is in the city of Englewood (Park Meadows area).