We are using dmsa and we use 1/8mg per pound, so 6mg is very low, and a good place to start. You can take all those supplements listed. Actually you may need more minerals, or a mineral support formula, unless you are taking more than listed here.
Side effects might be fatigue (gee we are familiar with this one anyone), irritable, yeast problems, and some complain of aching. For us it was just the tired part which went away with higher doses of vitamin C. And your C looks good. And of course, yeast. Probiotics will help but you might want to add something that kills yeast like Grapefruit Seed Extract or Candidase. A symptom of yeast might be constipation, bloating, gas, etc. You really want to keep the bowels moving when you are on a round, so add in whatever helps this. Be careful not to take the algin at the same time as the anti yeast agent or the dmsa. You don't want it absorbing that. And anti yeast stuff should not be taken the same time as probiotics.

Side effects noted for us: Usually irritability with the first dose or two, after that it is gone, unless we forget to take our vitamins. We take our daily doses divided up into four doses throughout the day. Mainly we see yeast develop which causes constipation, or irritability. Just keep the bowels moving and fight the yeast. Sometimes the first day off is irritable too. The fatigue we noticed more so on the second day of dosing but not the first or last. I am sure things might be different from person to person, but this is what we saw with the two in our house on dmsa.