Danger: Complicated hypothetical question
In my office there are some hefker chometz sandwiches on chol hamoed pesach and on a nearby intersection there is frequently a non jewish beggar (Beggar A).
1a) May I act as the beggar's agent (without his knowledge but for his benefit) acquire the sandwiches and bring them to the beggar?
1b) Is the pleasure of effectively giving tzedaka considered hanaah?
Once I take the sandwiches and get down the the intersection, Beggar A is not there, but Beggar B is.
2a) I want to be able to give to either beggar so may I acquire the sandwiches for Beggar A on condition that he is there but acquire them for Beggar B on condition that Beggar A is not there?
2b) In case a beggar that I had not considered is there, may I acquire on behalf of whichever begger is at the intersection that day without having a specific person in mind?
(Assume there will always be someone there.)