Relation/interplay of deployment pipeline stages (dev-stage-prod) with blue/green deployment mechanisms?
Yes.  With no QA and wanting to have an internal environment separated from production this makes sense.  However, a couple comments:


You should go for whatever is going to make your business money instead of going for an enterprise standard.  While some of the common practices may not be sensible yet, keep in mind that as your company grows (e.g. a dedicated QA role), they might eventually be very useful.
If you get rid of any stages, you are essentially eliminating a development environment.  Straight to production can be great, or greatly harmful.