Re: 433 mhz passive rfid system design, rfid, tag, reader,an
RFID standards are reserving 433 MHz for active tag communication, also according to the general usage of this band for SRD (small radio devices). This implies, that the power levels required for passive tag operation in the vicinity are generally not allowed by respective regulations.
Operation of passive UHF tags is dedicated to the 860 - 960 MHz range, or more specific 865 - 868 MHz in the EU according to EN 302 208 with an effective radiated power up to 2 W.
Regarding your specific questions, I fear that a deeper knowledge of RF engineering is required for the project, than it can be gathered by getting your edaboard posts answered.