Yes. Its a prescription medication, so ask your md.
Yes. I do this often for my patients who travel or are at high risk. Ask your physician for this.
I would. Although you need to start them in the first 48hrs, these meds do reduce the replication of flu germs and for many make the illness more tolerable. For about 30% the meds will not help at all, due to drug resistence. If taken too late, there is less benefit if drug sensitive.