A. The fifth item is the hero, assuming you are talking about the achievement. You can get look items from collector events and from offers, but you can't slot them with gems and they don't ever expire, and from the equipment trader for rubies. The ones offered in the trader give you the opportunity for your comm or cast to host another gem of your choosing. But beware that when they expire the slotted gem will disappear with it, unless you spend a handful of rubues to remove it before it expires.

B. No you are not able to do that for two reasons. The game doesn't let multi-accounting and even jf it isn't the same accounts owned by the same person it is steal incredibly overpowered as biggl players will send their outdated sets to those that would still use them. If something like this would ever be implemented it would take a few trunkloads worth of rubues to happen.