Yes charging at high currents is a bit dangerous that is why you need a computer controller charger that keeps track of charge, time, voltage and temperature.
Maximum fast charge for a NiMh is 1C. That is 1 x the capacity. So for yours that would be 6A. Mine were 6.5A but my charger maxed at 5A. I had a battery get very hot at 5A when I set my charge limit to 7500mah. So to keep it safe I went to 3A charge, max 6500mah input charge, and added a fan to the cells while charging.
Safe charging for NiMh is 0.1C so 600ma for your cells. This should take about 10 hours. This is considered normal.
Trickle charge is 0.05C.
A grid charger will charge all the cells at once and runs at ~350ma.
For comparison. The civic pack contains 11 pairs of 12 cells each at 6.5Ah.
Here is the write up I used as my starting point. There are some details left out and no pictures but it was very helpful.
Sucessfully Reconditioning an IMA Battery Pack - GreenHybrid - Hybrid Cars