A factor in your thinking will no doubt be opening times, so:
Anni Porsche Friday parties tend to run from 11am to 11pm and 2pm to 11pm on Saturday's.
Airport Girls parties tend to run from 11am to 4pm and 8pm to 3am on Fridays; and midday to 5pm and 7pm to 3am on Saturday's.
Insomnia run parties on different days with different themes. Unless you are into a particular fetish for the Friday/Saturday you are there, then it may not be the best option for a newbie and 1st time attendee. Thursday's or Sunday's would be a better day for a first taste and experience.
RO opportunities are best at AP in my experience.
In terms of etiquette, just approach respectfully even if you don't speak much German and you should be fine.
There's further reading in the Europe section here.
Hope you enjoy and do report back.