Is it dangerous to human beings because of the glut it contains? Do you have to be very careful while handling it?
It is dangerous in the sense that you should not be drinking it, getting it in your eyes, skin, mucous membranes, etc.
You should avoid direct skin contact, as irritation may develop.
As long as these precautions are kept, it is fine. You do not need any special handling equipment.
About using pure glut:
Isnt it hazardous to handle? Does it give out fumes and are they hazardous or is it harmful only if you come in direct contact with it?
I have only seen solutions of up to 70% (Sigma), I don't think there's anything above that. Is this what you mean by "pure?"
In any case, once it's above 25% or so, the fumes are quite hazardous and irritating. It is also corrosive at these concentrations.
Glut and Excel - do you have to manually dose it everyday or every other day? What if you could not dose it for a week for some reason? Will it harm the fish (maybe because of ph fluctuation)?
Ideally, it is best to dose it everyday.
If you cannot dose for a week, then your plants may start to suffer a bit.
It will not harm fish (by changes in pH), however, as it is a disinfectant, overdosing can harm livestock.