I'm no expert here, but I think scrubbing the barrels with borax or baking soda might help clean and deodorize them. Strong sunlight always helps too.

I saw a program on TV about surviving in Alaska where one of the people collected rainwater by securing a sheet of plastic between a couple of wooden poles then funneling rainwater into a barrel. It looked really neat and seemed to be working quite well. Sorry I don't know any more particulars like how you set up the funnel system.

Thanks aulani, I found an answer on a posting that simply said to take the barrel to a car wash and blast it until no suds are present. So far so good.
I use a impeller pump to push water from the catch barrel to the watering barrel. See link

Here is a link that might be useful: Impeller pump