a person shall be deemed competent to dispose of property if he has such an estate or interest therein or such general power as would, if he were sui juris, enable him to dispose of the property; and “general power” includes every power or authority enabling the donee or other holder thereof to appoint or dispose of property as he thinks fit, whether exercisable by instrument inter vivos or by will, or both, but exclusive of any power exercisable in a fiduciary capacity under a disposition not made by himself or as mortgagee;
(b)
a disposition taking effect out of the interest of the deceased person shall be deemed to have been made by him, whether the concurrence of any other person was or was not required; and
(c)
money which a person has a general power to charge on property shall be deemed to be property of which he has power to dispose.