Determine I2C read time
Disregarding start, restart and stop conditions, that transaction is 6 bytes times 9 bits. If the PEC is optional, it's 5 bytes * 9 bits = 45 bits. The start, restart, and stop conditions may not equal a bit in duration, but can be roughly approximated as equaling a bit. So I count 48 bits, and in practice there is some software overhead.
So your estimation of 49 bits is approximately right, you can read a 16-bit word from the chip about 2040 times per second, or about every 0.49 milliseconds.
Keep in mind that this is the theoretical maximum throughput of the bus. Any other things that the software does will slow it down, and also if the slave needs to stretch the clock to slow down the communications.