There's all shapes and sizes, colours and creeds there, so don't worry about that. The lighting is subdued and everyone is looking at the girls.
The girls are proactive at inviting you to join in the action, it usually means a few FFM 'spitroasts' at the start if the party is full, i.e. 14 guys and 7 girls. It's often less than that, my 2 recent parties had 10 & 11 guys with a couple of them either arriving late or leaving early, so it was pretty much 1-2-1s all the way and the occasional FFM until someone else came along to claim the spare girl, I did get 4 girls on me at the end. It's group sex so the action is quite fluid, everyone expects to share if it's busy. The MFMFM daisy chains are fun too.