AXI 4 protocol - can read transaction and write transaction occur at the same time?

AXI 4 protocol - can read transaction and write transaction occur at the same time?
Sure, of course.
can 2 or more wrirte transacation occur at the same time?
No, write transaction uses write channel, they must be sent in order.

Under the assumption that by "occur at the same time" you mean "be outstanding at the same time", then the answers to your questions are:
>>AXI 4 protocol - can read transaction and write transaction occur at the same time?
[S] Yes
>>In addition can 2 or more write transactions occur at the same time?
[S] Yes

NOTE:
- A read transaction is defined to be outstanding from the cycle in which ARVALID/ARREADY handshake happens to the cycle in which the last (as indicated by RLAST) associated RVALID/READY handshake happens

- A write transaction is defined to be outstanding from the cycle in which the earliest of AWVALID/AWREADY and WVALID/WREADY handshakes happens to the cycle in which the associated BVALID/BREADY handshake happens