No, nitrofurantoin is an antibiotic used for bacterial urinary tract infections. It would have no effect on a viral disease such as herpes.
There is no vaccination for herpes. The only way to make sure you don't catch it is by not having sex at all with anyone infected with the virus.
no there is no cure for herpes
The second person will get it at the point of contact with an active lesion. If someone has it on their mouth and goes down on someone else, there is a good chance they will develop genital herpes.
No; but you can get oral herpes in the genitalia and visa verse.