I am not a doc, or even in the med field, this is the 1st time I've done any assisted repro stuff -not even IUI before this, our 1st IVF. I know how daunting it all can seem, but if you check out your docs, clinic on the SART web site, it gives you an idea of general success rates it may guide you to the answers you are looking for- in fact, call them and ask - it is in their best interest to give you all of the info that you request.
I am sure age is a factor in deciding what hormone protocol each woman is on( how aggressive they are, for instance), however - it is uniquely catered to your body's needs.
The REs do all of the prelim bloodwork, hysterosalpingogram, ultrasounds,semen analysis, your personal history, and with that, they decide what protocol you would be on. I am sure that some offices/clinics have preferred meds - GonalF vs. Follistim, but from what I have read, they are very similar.
That being said, as each of us is different, as is our situation (ie: male or female infertility issues), the REs use their knowledge to cater what might work best for you.
As even we change each month, they may not get it right the 1st time, or even the 2nd, we just hope and trust that they are doing what is best for us to achieve our goal of a child.
best of luck to you, -give some REs a call!