If they are all from the same lot and are all unused, then paralleling for charging is no problem. Paralleling for use is most likely not a problem. But storing them paralleled will cause the one with the weakest electrolyte to drain all of the other ones over time.
If you're not comfortable charging full current, add a small resistor in series, around .2ohm. See where that puts the current and adjust to get your 600 ma each.
If your wire connecting the batteries together is heavy enough, order shouldn't matter. to be safe about voltage drop in the connections, parallel batteries in s row and connect neg at one end and pos to the opposite end
If you're not comfortable charging full current, add a small resistor in series, around .2ohm. See where that puts the current and adjust to get your 600 ma each.
If your wire connecting the batteries together is heavy enough, order shouldn't matter. to be safe about voltage drop in the connections, parallel batteries in s row and connect neg at one end and pos to the opposite end