No, amandam isn't a valid form of amandare. It resembles a first person future or subjunctive, but since the verb is a 1st, it can't be. I'm pretty sure that amandam is the gerundive (just like the name Amanda--the one to be loved). Besides, it would be active anyway, and would take a dative as its object since it's a compount (ab + mando), and there are no datives there. Also, the "must" construction, passive periphrastic, is only with an esse verb. Of course, esses are often supplied in poetry.
The omnia also clearly sounds like an omnia to me, which makes sense considering it would agree with tragedia. Homme is not a Latin word (it's French).

I hope that helps.