What a great question. As a general rule, it's good to flip positioning of iconography for RTL languages. So your bottom option, with the chevron on the left, is correct.
If you're curious, I'm basing this answer on lessons learned running as lead designer on multiple projects with the NYC DOE and NYC mayor's office, where all projects have to support 11 ...
Seconding Ben's answer, if I understand the Material Design bidirectionality guidelines correctly then it should be mirrored:
When a UI is mirrored, these changes occur:
Text fields icons are displayed on the opposite side of a field
Navigation buttons are displayed in reverse order
Icons that communicate direction, like arrows, are mirrored
I find it is best to include the UI back button by default (for the reasons listed by @Tin Man as well as parity and operational efficiency when designing an app for both iOS & Android). However, you should consider the implications of doing so on a screen-by-screen basis.
Additionally, you may want to specify different actions for the hardware back ...