Configuration of ESP8266 nodemcu v3 I2S with 74HC595 shift register and max485 modules

I am starting the adventure with esp8266.


I want to use I2S and a 74HC595 shift register controlling 8 modules with max485 - to send 8xDMX512


Please give a hint to wiser heads if this is feasible.


WS signal - controls the latch on the register


connections
74HC595
14 DS Serial data input (SD)<--
12 ST_CP Storage register clock input (WS)<--
11 SH_CP Shift register clock input (SCK)<--


ESP8266
I2S
GPIO3/RX0 Data bits (SD)-->
GPIO15 Data bit-clock (SCK)-->
GPIO2/TX1 Word select (WS)-->


WS controls the latch.


And now the question

1 Is the I2S rate setting correct (data on register latched every 4 microseconds)
i2s_set_rate(250000);

2 Is the 74HC595 sliding register able to operate correctly at this speed ?

3 If yes - is 5v necessary for it (or is 3.3 enough)