- Am I correct with visa type and duration?
Yes for "two entries", but it sounds like the "duration of intended stay or transit" should be 2 days, because there are only 2 calendar dates on which she will be present in the Schengen area.
- Does she need to book an accommodation in AMS? She's not going to stay overnight in AMS not a single time.
No -- she should definitely NOT book any such accommodation for her application. Doing so would be inconsistent with the travel plans she's otherwise presenting, which would raise suspicion of foul play and probably lead to the application being denied with the "Justification for the purpose and conditions of the intended stay was not reliable" formula.
- Does she need to provide accommodation confirmations for Serbia?
That would definitely be helpful. She's supposed to attach an itinerary anyway, and this itinerary should be for the entire trip. Having concrete plans for what she will do and where she will stay in Serbia will help convince the consular office that the Serbia trip is not just a pretext for getting into Schengen.
- She has clean passport (no visas), would you consider such application risky?
We can't say. The main risk here is probably whether her circumstances in her home country make her look like an immigration risk or not, based on the documentation she submits.
She needs to provide documentation of her economic and social circumstances which makes the consular officer able to conclude, "someone who has those conditions to return to would not find it attractive to try to be an illegal immigrant in one of the Schengen countries".
She will also need to provide some documentation for what her connection to you is, to substantiate her claim that she wants to enter the Netherlands to visit friends.