Recepcionista: ¿Qué puedo hacer (1) [para] usted?
Cliente: Quisiera reservar una habitación.
Recepcionista: ¿(2) [Para] cuándo la necesita?
Cliente: (3) [para] el 2 de agosto.
Recepcionista: ¿(4) [Para] cuántas personas es la habitación?
Cliente: (5) [para] dos.
Recepcionista: ¿(6) [Por] cuánto tiempo la necesita?
Cliente: (7) [por] una semana completa.
Recepcionista: Muy bien. ¿(8) [Para] quién es la reservación?
Cliente: (9) [para] el señor Jiménez y su esposa.

01. para: in order for (We would not literally say 'in order for' in English, but this is the idea. We are not doing something because of them but for them.)
02. para: fecha límite (With 'por' it would mean around a certain date.)
03. para: same as 02
04. para: in order for (We would not literally say 'in order for' in English, but this is the idea. The room is not there because of them creating it but for them to use, i.e. they are kind of receiving the room as well.) 
05. para: same as 04
06. por: plazo de tiempo
07. por: plazo de tiempo 
08. para: same idea as 04; (To contrast, the reservation is not because of them but it is for them to receive.)
09. para: The reservation is 'for' señor Jiménez y su esposa not because of them.

Additional note:
- El libro fue escrito por Octavio Paz.
- The book was written by Octavio Paz.
Authorship uses 'por.' In the above activity in certain numbers, if 'para' were switched for 'por', it would kind of indicate authorship, and that is certainly not what is being expressed.