Why does a stream cipher have to be deterministic?

Question $2[9$ pts$]$

What is potential problem with using the same Key and Nonce $($IV$)$ values in two different encryption operations of a stream cipher?

Question $3[9$ pts$]$

What are the types of stream ciphers in terms of target platform? What are the advantages of each? Provide the example implementation names for each type.

Question $4[9$ pts$]$

What does a Feedback Shift Register $($FSR$)$ do$?$ What are the differences between Linear FSR and Filtered FSR$?$