I’d use theseTapconscrews instead of anchors. They work fine, a regular drill will work, you can buy a package that includes the right size drill bit. Mounting a piece of pressure treated wood is a good idea, but no need to turn this into a major effort, you should be able to drill and screw into brick with only slightly more effort than wood.
Expansion anchors create both compressive and tensile loads within a brick. In the brick adjacent to the fastener, the stress is compressive in the radial direction (due to the expansion of the anchor) and tensile in the tangential (or “hoop”) direction. The brick in this case is sort of a thick-walled pressure vessel, but not quite. In reality, the stress state is pretty complicated in the area around the fastener.
An expansion anchor in brick isn’t inherently problematic despite the tensile loads. There’s enough material around the fastener to handle simple fairly high forces, however those forces get reacted out and turned into stresses.
I would absolutely use stainless fasteners here if I could find them. Metal oxides (like rust) typically take up more volume than the unrusted metal does, which can act as an additional expansion load, theoretically causeing the brick to crack.
That seems unlikely to me, but for an exterior fastener that’s likely to get wet regularly, stainless makes sense. Stainless steel can (and does) rust, but it’s a lot better than zinc-coated stainful steel.
Yes. The problem is less the anchor walls pushing out radially, as the anchor stretching the diameter of the hole - the tangential tensile force.
I assume he’d be hammer-drilling … all night long…