Stormtide_Leviathan

It's certainly possible, though in the past centuries/millennia there were tons of attempts to replicate shards. In fact, I'm pretty sure fabriology as a whole began as an attempt to replicate radiant powers. So I feel like their must have been countless experiments with involving fabrials and shards, so it seems unlikely something like this hasn't been tried before, though certainly not impossible. Duralumin wouldn't be a metal people just have lying around, so I suppose that could be the key like you mention, but even then it just feels narratively cheap. "All you need to bring back dead shardblades is this cool new metal", I'm just not sure that works with Brandon's style. It feels like it would be something more narratively-driven

Really depends on your perspective. To me, it seems much more that the powers are in the hands of elite. Rashek gifted allomancy to the nobles who supported him, and it stayed in Noble lines. In era 3, presumably, people will be able to buy powers. Era two is the most deviant but even then the new noble lines seem to be the strongest- there's a reason that [ERA 2 Spoilers] most of the woman captured by the set for what we think is mistborn breeding potential are nobles; they're all descended from spook. There's definitely some level of "those with power become the elite" though, don't get me wrong.

It does seem very likely that allomancy and feruchemy become rent-a-power as people are mentioning here, and I think it's very interesting that thematically the powers keep ending up in the hands of the elite one way or another.

Copper or Bronze seem the most applicable to my every day life, but Chromium, Pewter, and Steel I could have a lot of fun with

Even if it's not (though I don't see why it wouldn't be), there's still some highly fascinating stuff in this area. What happens if a blind person taps a visual memory? Or if someone without iron/steel allomancy taps the vision of someone burning one of those metals, with regards to the blue lines?

Feruchemical or allomantic abilities aren't tied to the body, they're tied to the soul, so I doubt spiking yourself to a dead feruchemist would give you feruchemical abilities; it would likely have to be a living feruchemist. Kelsier clearly got feruchemy from somewhere though, so it's possible he did just that. This would probably have a lot of strange ramifications, since you have two souls stapled together. However, I think there is a workaround. Say you have a willing full feruchemist. They completely store their Identity using an aluminum mind. Then you use hemalurgy to staple yourself, a cognitive shadow, to this person (likely using a duralumin spike, since it steals Connection/Identity, but I digress). I think this would give Kelsier the parts of the soul with feruchemy with none of the idenity-mashing side effects. But this is someone else's body, so why would he have scars? Easy solution: gold feruchemy. Since it works by making the body conform to the person's spiritual ideal (filtered through the cognitive), and since the blanked identity of the host body wouldn't get in the way, this means that as Kelsier uses gold, he will make himself look more and more like his original body. This would almost certainly give him the scars like the original post was talking about. Now it would be difficult to find a willing person, particularly a willing full feruchemist. However, if one was ever born (which I don't think is too unlikely in the years directly after the Catacendre, before the genes got all crambled together with allomancy genes), I think Kelsier has a good shot at having them be willing considering there's a whole religion about him and he just proved to you he could survive even death.