Note that Storages in different towns are not linked, so you have to plan your long-distance travels wisely.
The quantity of items you can store is determined bu the Storage level of the town you're in (up to 750 in weight for a level 5 Storage).
A Warehouse is a common storage for your gang where you can store items up to 4 300 in weight.
Every item in the Warehouse has a member level requirement (from simple Member to Leader), decided by the member who stored the item. Members with rank of Rookie can only place items in, but cannot take any items from the warehouse.