Hapkido DOES teach good ground fighting techniques, however it is not anywhere near as complete as, say, gracie jiujitsu or the such. It's still more than adequate for anything involving self defense, and ive found that jiujitsu is readily useable in hapkido groundfighting situations. Long story short-yes it does teach ground fighting, and any jiujitsu or werstling knowledge you can get can be thrown in without any modifications. You see a move in jiujitsu you like, like on UFC, you can practice it in the Do Jung. The do jung I go to has an instructor that was a jiujitsu blackbelt though, and a russian sambo judo blackbelt, so it kind of depends on the school's instructors.