Shielding and wiring questions

No benefit to heavier shielding.
Be careful... the jack and tip of the plug are very close to the side of the cavity, and it is not uncommon for there to be shorts against foil shielding in this area.
Honestly, I would not bother with the jack cavity, but if you insist, I'd put a layer of tape around the top curve.
Another trouble spot is the control cavity below the switch, but there is enough depth on a Corona/MiM body for that not to be a problem, likely this is only an issue on the thinner Squier bodies.

 

I have a 56 American Vintage Strat which I added copper tape shielding. I fully did the whole cavity and I also used the copper tape to just extend what aluminum tape that was already on the pickguard. Make sure you buy the tape that has conductive adhesive. It made a big difference and cut down the humming. I'm not sure about the solid Aluminum shield but the tape works good and won't raise your pickguard. As for worrying about the dust, well my pickguard is an 8 hole so has slight gaps that I guess dust could get in but never had an issue.

As for the wiring - yes its preference, I kept mine original with the vintage wiring.

 

Did not notice any tone change at all, just cut the noise

 

Copper foil is the best, and you can solder to it.

Put a piece of electrical tape over where the tip of the cord might touch it.

 

If the wiring is done properly, there it the potential for a small improvement.
"Properly" being defined as pickup leads, and the run from the volume pot to the jack being twisted, and keeping the single runs of "hot" between the switch and pots to a minimum.
Your pickups are the source of most of the noise, and shielding the main body cavity can reduce anything picked up from behind.
The short lengths of wire in the control cavity are too short to really amount to much of anything.
Unfortunately, you can't shield the top of the pickup

But keep in mind that AC hum is 60hz. That wavelength is measured in yards... actually miles. 60Hz has a wavelength of 5,000 kilometers.
Even at 1/4 wave, it's 1,250 kilometers. A grounded chain link fence can protect against that.

Of bigger concern, and more today than in the 70s, are sources of higher frequencies, such as 2.4Ghz WiFi, which is closer to 5" for the full wave.
Computers, light dimmers, fans with electronic power supplies... Everything that we have grown to love that didn't exist in a typical home in the 70s is a potential noise source.

 

I use the aluminum duct tape you can get at your friendly neighborhood home improvement warehouse. Al is superior to copper when it comes to filtering "buzz" and it's a lot less expensive than the copper tape you get from guitar parts suppliers. When applying, I put a small cut in with an X-acto to fold a tiny portion of one layer into the other at the seam between overlapping sections to create a contiguous shield and it's worked beautifully for me. Screw in an eyelet with a ground lead attached to it and Bob's yer uncle.

 

I used the copper tape with the conductive adhesive and shielded the pickup and control cavities as well as the whole back of the pickguard. I grounded the cavity shielding to the trem claw using that wire that should be there already and extended some of the cavity shielding up onto the top of the body in a couple of places so that each tab covered a pickguard screw hole and poked a hole in the shielding where the screw hole was. That way when the pickguard is installed, its shielding makes contact with tabs from the cavity shielding which is already grounded to the trem claw and controls. I saw this in a video or it might have come with the instructions for the shielding.

A lot of manufacturers use shielding paint which is that black paint you see in the cavities. I don't trust it but a lot of folks swear by it.