Well the first thing to do is trash the 2400's, those are hopelessly outdated and not even good to use for practice. The 3000's are only bairly good enough for practice and you would'nt want to use them in a race.
Most peeps charge at 5 or 6 amps, check the CE website and print a downloadable user manual for your gfx. Its a very good mutiuse charger and will do everything you need for ni-mh. If your batts have the labels on them use the same discharge rate that the battery reseller used, usually 30 or 35 amps.
Also its a good idea to use an equalizing tray after you discharge, that way you get a more even and full charge.