[Capbill]

Hondata is pointing out the two wires that come from the ECU board to the manifold. The so called 'grounding kits' do NOTHING to improve this specific path. Anything to the battery ground does not improve current return path while the engine is runnning since the alternator/ its mounting bracket is the source of + voltage & thus the return path has to be good going back to it.
If the two ground wires to the manifold are loose or corrosion starts to impair the current path then when that current is shunted to the ECU case thru the body that current could damage the circuitry on the board.
If one removes those wires to install the IM gasket then one must assure that the connections are tight.
I have seen a couple year old never disturbed grounding bolt on the engine block directly to the ECU, have corrosion under it such that the ECU controlled fuel pump relay would not activate & thus the engine cranked but would not run.
I question the redirecting the wires to the valve cover instead of the manifold since the torque of the bolt on the valve cover would be less than to the thicker metal of the manifold. Also, the aluminum valve cover expanses & contract more than the steel bolts thus tends to loosen the bolts.

 

[Capbill]

no, hondata states that the 7? bolts are providing ground. I have a plastic manifold & it is still not grounded to the valve cover so the gasket is a non-issue. I would parallel it to the engine block, not the valve cover for the above stated reason, but not remove it from the existing location.

 

[Capbill]

Yes. When current is flowing, there is a voltage drop even a very small one since there is always some resistance however small in the wire/ metal path. Since the alternator is the source & is charging the battery, the voltage at the alternator output is say 14.4 v, at the mounting bracket 0v, then at the battery hot terminal it is 14.39v(battery 'stand alone' voltage is no higher than 12.5v) & at the battery ground terminal +.01v. In fact there would be less voltage drop in the system if the battery was disconnected completely since it is always being trickle charged.
The shop manual schematics show the common grounding point being the engine block & the body. Thus it is important to have good connections at all block & body connections more than at the battery.
Of course, to start the engine the battery is indespensable.

 

[Capbill]

My take is
no.
Ok, will not hurt.
Maybe a wire to the block in parallel from the intake but I think that to the valve cover is subject to loosening.
Batt to block will help for starting but nothing for running as I explained earlier you already ran the extra wire.
No, since you already doubled up the block to body one.