Clarification on radiation shielding: you generally don't use just a hydrogen rich layering, there may be metallic layers as well (such as the craft's outer skin, tankage, etc). But most of the high energy solar and GCR is charged particles, mainly protons. The lower end of the energy range will almost entirely impact whatever shielding you use, creating a small shower of secondaries. Some high energy particles will impact, some will pass right through. Those that pass through will most likely pass through everything, and those that do impact crew will mostly impart only a tiny fraction of their energy to them. Those that impact the shielding create an ever-growing shower of secondaries; where the secondaries aren't sufficiently blocked poses more of a risk to the crew than had the particle not impacted anything at all on the way in. Primaries at over 10MeV or so are particularly prone to kicking off secondaries, and once you get into hundreds of MeV spallation starts becoming a significant component.
All of this together means that the most important particles to block are the secondaries, in that they're more numerous, less likely to cause negative side effects by blocking them, etc. Heavier secondaries like alphas are easy to block, while it's unrealistic to block a significant fraction of high energy gammas on something as light as a spacecraft. This leaves the neutron secondaries as your prime target for elimination, which can generally be captured if moderated down first, but otherwise pose a risk to the crew. The lighter the element and the higher the cross section, the better the moderator; also, the lighter the element, the more you can carry on a spacecraft. Hydrogen fits all three bills well. Once moderated down, then the capture cross section becomes key. Hydrogen can manage thermal neutron capture over a sufficient distance, but far better is something like boron. In fact, metals can sometimes be counterproductive, especially on the inner side of the shielding. They increase the risk of spallation, bremmstrahlung, and your neutron captures are much more likely to produce short half life isotopes which will then undergo beta- decay.
There's no need for an unusual amount of metal in the shielding (over what would be needed to build the craft itself), and no need to make it a faraday cage. EM radiation and charged particles are very different beasts.