The game is playable on high settings on my vintage Mobility Radeon HD 3650, so... The performance drop on my system is about 15%. I recommend testing what effect has lowering SSAO. EDIT: Yup, tested it myself. Dynamic shadows + SSAO gives serious performance hit. Disabling SSAO makes the performance drop minimal! So for lower-end systems I recommend disabling SSAO or at least setting it to minimum - Medium resolution and 4 samples, for example.
The color:
You are free to edit the color in the model editor (Diffuse color). It's the easiest part.
http://www.moddb.com/mods/dynamic-shadow...n-mod-wip2