To transport leeches a small plastic container with a lid works the best. A medium sized container can hold several dozen leeches. Add the leeches and then cover them with fresh water. If you are trying to keep leeches healthy for a trip that may span a few days time it is important to change the water in the container every day. Also, avoid tap water as the chlorine will kill the leeches.
Bottled water is probably the best way to go.
Also, keeping the leeches slightly chilled will ensure they are fresh when you are ready to use them. Second only to night crawlers, minnows may be the most effective live bait there is catching the attention of the widest variety of game fish. Minnows of various shapes and sizes are available to entice everything from perch and crappies to pike and steelhead. Transporting and caring for large numbers of minnows is very tough. The most important consideration is supplying enough water and oxygen for the minnows to survive.