You have asked several questions at once so a little difficult to give you the answers you want.
First, Hardy backer board is a newer, lighter, substitute for concrete board and usually used in bathrooms and under tile installations. I have never seen it used on exterior walls as a sheathing.
Second, the huberZip system is from Advantec. I love Advantec sheathing and subflooring. I'm sure it does what it says, but it is pricey compared to OSB sheathing and tyvec. Selecting a product because of price is not what we do here. An OSB, or any T&G exterior sheathing with properly installed and taped Tyvec or a house brand wrap also works very well.
Third, a true vapor barrier is installed on the heated side of the wall studs, not under or over the exterior sheathing. the wall cavities and insulation must have a a way to breath. They will breath and excessive moisture should escape through the exterior siding. Tyvec is not a vapor barrier, it is an air penetration barrier, just like the new Zip system. they both stop liquid water infiltration, but water vapor is a different story, it must be able to pass through. On wet, foggy or very humid days, humidity gets into the wall cavity, the vapor barrier keeps it out of the living space. When the weather conditions are better, the moisture migrates out of the wall cavity through the siding, thus drying the wall.
I hope this has answered some of your questions. Good luck on your project.
I have hung a 4x8 ft trellis spaced 3" from the wall and supporting a large climbing rose on the side of my house through the vinyl siding. No leaks, and has been there for 6 years. Here's how:
Firstly, my vinyl siding is not flat. Each vinyl "board" has an upper section that is flat to the OSB sheathing of the house, and a lower protruding section that is spaced about ½" from the sheathing. Drill your holes to accommodate the screw through this upper, flush-to-the-sheathing portion of the siding, so that the sign will not compress the protruding portions of the vinyl siding.
Fashion a short "standoff" that will space the rear of your sign the same distance as the most protruding part of your siding. I cut short lengths from a plastic toilet infeed pipe for the tubular standoff, but you can probably figure a dozen ways to do this.
Put a dab of silicone or exterior caulk on the end of the standoff that will sit on the siding. Pass the screw through the sign and the standoff and fasten into the sheathing. Done!
Best Answer
Re-nail the bottom of the T1-11 to the sill plate every 6 inches. I use Simpson StrongTie ring shank stainless steel siding nails. Be sure you know where any water pipes and drain lines are in the exterior wall, and use the length of nail that would not go much more than 1 inch into the sill plate. You could go 1.5 inches into studs low on the walls where there would be no pipes or wires.
Simpson StrongTie stainless steel siding nails