Help with TFHE multiplication

Question

I am trying to understand TFHE and realise that TFHE supports three types of ciphertexts:

1. LWE : supports additive homomorphism and multiplication with constants
2. RLWE : compact version of LWE
3. RGSW : supports multiplication of two RGSW ciphertexts or external product ( RLWE with RGSW). My questions are:
4. Does TFHE support homomorphic multiplication of two RGSW ciphertexts only and external product? This is supported by signed digit decomposition
5. Can TFHE support multiplication using relinearisation technique like BGV?
6. in the signed digit decomposition technique, how is beta determined that divides the polynomial into smaller ones? Any good explanation how the technique is used? How is it different from BGV based scheme multiplication?