That would depend on who gets to decide what counts as "a good cause". I can think of worse ways the purchasing power could be employed than distributing it widely among other users of the currency. Even assuming the best of intentions, you're still directing resources rather arbitrarily away from other goals in favor of the selected cause, which is not necessarily a net benefit to society.

In general it makes sense to follow the wishes of the deceased, if they are known—it serves no good purpose to distinguish between gifts made just before death vs. ones made at the time of death via a will, and doing so penalizes those who die unexpectedly before making their bequests. Beyond that, I see no reason why relatives of the deceased should have an automatic claim in the absence of a will—but their claim is stronger at least than any the state might make, so given the choice I'd rather see the property go to the heirs than the state. Personally, though, in the absence of a will I would just consider the property abandoned and available for anyone to freely use and thus claim for themselves via homesteading. In some cases that process may have already begun—for example, if the owner of a house dies without leaving a will then anyone else who was already living there (presumably the deceased's family) would have priority to assume ownership once the deceased's claim was abandoned. Their prior investment in the home didn't matter as long as it had an owner, but with that owner gone it should count in their favor for the homesteading process.

Yes, but the dependency on what counts as a good cause also applies to distributing wealth indiscriminately among all holders of a currency.

"Capital" is the wrong word here. It doesn't include non-productive, consumable goods such as food, but it can include money as a stand-in for means of production. It doesn't make sense to contrast "capital" with "money" when what you really mean is "all goods which are not money".

In any case, the difference is utility. The value of money is (almost) entirely derived from its use in trade; it's not consumed and it doesn't directly serve as a means of production. If a factory burns down or food spoils then society is poorer for it, but if the amount of money in existence decreases then nothing of value is lost, provided it affects everyone holding currency equally. (In the case of someone dying the only one not affected equally is the deceased, who isn't around to object to the loss and thus doesn't count.) We still have all the consumable goods and means of production which we had before, and the purchasing power of the remaining currency will adjust to compensate for the change in the money supply.