zurkeyon:
https://www.amazon.com/gp/product/B0057OC66U/ref=ox_sc_act_title_2?smid=ATVPDKIKX0DER&psc=1
This one appears to have opto-isolation, and is very inexpensive.
Correct.
Appears to have, but doesn't have.
The optos on there are just for decoration.
Leo..