One shouldn't choose an unlearned lay-person for the job: Pesachim 49b
The Collecor's daughter is desirable for Marriage: Pesachim 49b
Procedures
The Collector shouldn't exchange the leftover perishable coins to himself, because of Suspicion: Pesachim 13a; Bava Metzia 38a
The Collector's hand, as the "hand of the poor": Kiddushin 27a; Bava Metzia 11b
Town Collections
The obligation on passersby, where they are travelling as individuals or as a group: Megillah 27a-b
Beyond the Laws
Better to be a collector of Charity, than the one who has to choose who gets Charity: Shabbat 118b