The rules constantly seem to change, but with a 8 hour layover you should ask about whether you have priviliges to eat at the Emirates run restauraunt or use the Marahba lounge. I know for a fact that there is a buisness class lounge that will let you in for $25. I chose to use the showers at the hotel (which was about $8 for a half hour) because I didn't need to eat at the buffet.

Star does indeed have a lounge, if you are prem ex and flying on Star you should have access. Even if you aren't flying on Star, you can always ask politely and hope that the lounge dragon is in a good mood!