(a) Coanda effect has relevance indeed .... even without any pressure difference between upper/lower side, the curved shape generates lift
I don't think so. Else, how do you explain Jonkster's last comment in Post #21 ? If you don't have a pressure delta, you don't have a force. You really don't need to appeal to Coanda, the effect is explained with reasonable ease by Newtonian thoughts.
While you can impose a force directly on a solid due to its ability to withstand shear stresses, that is not feasible with fluids, either liquid or gaseous. In the case of a fluid, there must be a pressure gradient or delta over a region for a force to be developed. With a moving fluid turning a corner, there is a transverse pressure gradient which does the honours - hence the usual graphics associated with flow over an aerofoil.
Can you offer any objective evidence (say, pressure tapping data) to support your theses that even without any pressure difference between upper/lower side, the curved shape generates lift and try with a spoon under tap water flow, where pressure is the same on the upper and lower side of the spoon (it is the athmospheric pressure, both for the water side and the air side ) .
(b) lift is created just by deviating, the incoming water flow, which obviously creates a dynamic pressure. But this is not very relevant to what an aerofoil might be doing ?