Creating freeRADIUS extensions (beginner)

Hello. I'm doing my thesis project on advanced authentication techniques. I want to use freeRADIUS to implement extensions regarding one or more of the following: 1)Location-based authentication 2)Prepay codes for timed access 3)QoS parameters (allocate network resources according to the user's services) Do you think these extensions are 'doable' for a beginner? What are the major steps in implementing a new module? From what I've understood so far, I have to create a .c file and add some attributes to the dictionary. Is implementing new message types difficult? (does the finite-state machine need to be modified?) Any advice/information/tips are greatly welcome. Thanks!