Thanks for the questions, last! I've never dealt with an enema, so I can't help you on the specifics, but how I deal with the mess is to use a condom whenever we do anal. It provides a bit more slickness for ease, can throw it away once done, and it prevents exchange of fluids (cum can irritate bowels, leading to the runs).

The one question I can attempt an answer for is how often to do one...as long as you're eating normally, you should have a movement every day or so, so I'd expect that yeah, you'd have to do one each day to be clean. I don't know how many hours it would stay empty, probably depends alot on when you last ate and what.

Hope it helps,
EB