I had a look around, and these seem to be their names as they use it commercially:
- 田中フミヤ, たなかふみや
- 石野卓球, いしのたっきゅう
- 電気グルーヴ, でんきグルーヴ
I couldn't find all of them, and some seem to use their names spelt in Latin script even in Japanese itself; others seem to spell their names in katakana
very often, too. It's also interesting to note that the names you gave are in Western order (personal name + family name); in Japanese, the order is reversed (family name + personal name), except for Ken Ishii, which seems to be known in the music industry by that even in Japan.
As for pronunciation, since you said you don't study Japanese or anything, the best approach is to read the names as you gave them using English as a model for the consonants, and Spanish as a model for the vowels. 'Groove', in Denki Groove, is spelt 'Guruuvu' in Japanese, but it's more likely to be pronounced 'Guruubu', with a B, by the average Japanese speaker.