1. Could I just run the tlc5940 signal lines to each lamp? or would the distance of >10ft degrade the signal too much?
2. put an arduino inside each lamp and connect all arduino's with the spi bus and have the master send out commands to six slaves.
1. Best bet is to try it and see as it won't cost anything to do so. Might need to slow the SPI clock speed to be reliable.
2. Maybe you could use something like MAX232 chips on the SPI CLK/DATA lines at each end to extend the distance of the SPI and save expense of extra Arduino's.