You don't "have" to take any of those. They play a specific role in your cycle and you simply shouldn't just throw stuff in if it doesn't serve a purpose.
You said "ew" = "every week"... 100mg every week? that's nothing, baby dosage.
Arimidex is an anti estrogen drug, some people need it and some people don't. Should be taken if you have estrogen related issues.
Proviron has another purpose too...which you can easily read about on google.
But - I do think the dosage 100mg/ew is really low.