This is my QFS (feng's 37-key blank zinc + modifier kersite from Banggood // I also have 3 StarCraft zinc keys on it, not pictured):
Will this set makes the keyboard heavier?
Yes. Definitely not something to take with you places, but it's considerable when compared to picking up my KeyCool with PBT caps. I personally like the heft.
Will this set makes the switches easier to press? (Added weight)
When I first got my zinc keys, they were on blue switches. At that time, I would have said they made pressing the keys more effortless. However, my QFS with greens kind of balances out the weight. They're neither harder nor easier to press in essence. I haven't yet moved them to my KeyCool with clears to see what that might feel like. But ultimately, it'll depend on what your Poker II has for switches.
Will this set wear out fast or will i be able to keep it a long time? Versus ABS? Versus PBT?
There was a reddit post detailing what happened to zinc keys, but honestly, that was simply a case of not caring for their property. I personally went for blank zinc keys, one for the look, and so the chance of corrosion under the coating was less likely in the "legended" portion.
I think under common sense care, they'll last just as long as any other type of keyset.
Does this set really looks like the pictures presented? i mean, is it as shiny?
Can't speak to this, as I have a different set.