Maybe I'm a bit of a pedant, but names typically cannot be translated. They can only be transliterated into other writing systems, or mispronounced in whatever way native speakers of another language would be likely to do so.
I'm curious, why exactly do you want these names and this Indonesian word transliterated into Japanese?
Grace is usually transliterated as either グレース or グレイス, not as グレス. Either of the first two are fine, and they are spoken the same, so go with your preference.
Torres is usually transliterated as either トーレス or トレス, depending on how long the first vowel sound is when spoken. トーレス is probably better.
Sufjan Stevens has his name transliterated as スフィアン. If your friend's name sounds similar, then go with that.
Sayang is usually transliterated as サヤン, not as サヤング.
Edit: Regarding your question about a space, you can add a space, or put a dot between the words, like this: グレース・トーレス