Can I do bitwise operations in VisSim?

Yes, use Boolean AND and fixed point shift

The Boolean operators and, or, not, xor all perform bitwise arithmetic. You can also use C-style hex constants in a constant block. So an and of 0xFF will mask off all but the lower 8 bits of an integer like this: bitwise and

Here is an example of reading a single 32 bit value from the digital GPIO in port on an F28335 and then writing it out as 4 bytes on the serial port. serial transmission of 4 sequential bytes of long integer
The order of execution of consumer blocks is top down, so bytes will be sent from low order (byte1) to high order (byte4).