Radical names and stroke names Sometimes a character component has one pronunciation as a Kangxi radical, another one as a stroke, and perhaps even more:


一: yī / héng
丨: gǔn / shù
丶: zhǔ / diǎn
亅: jué / shùgōu
乙: yǐ / héngxiéwāngōu / zhé
乚: yǐ / shùwāngōu / yà
乛: yǐ / hénggōu / zhé


Which names are used in practice and understandable? Should I learn all the variants or only one of them?
Actually we only use the name ( the second ones in your question) which describes the shape of the radical. It's how teachers call these radicals in classroom. 
Many radicals,  like 丶, are not treated as charterers. Although they may have a pronunciation, most Chinese don't know that.
Even for these radicals which happen to be characters, we still incline to use the name referring to the radical, rather than its own pronunciation. It would sound ridiculous when you describe the strokes of a character, say 王 this way: 三个一，一竖. Instead, native speakers would say: 三横一竖.