Does a person need to make a declaration to use the kinyan of dalet amot or not?

Can dalet amot work by all kinyanim or only by gitin vkidushin?

What if a malveh says throw me the money and you get off the hook?

Halacha gimel - no sharp utensils used to cut Peah. (Safety of the poor people is very much taken into account)

And three designated time periods for collection. More or Less.