Hmm... just wanted to address air-sharing. Sorry don't have much to add to the answers given for the initial questions.
Oh, the triglide keepers on the back of the plate are a good idea to keep the shoulder webbing adjusted correctly. If they become loose, your rig may start shifting around.
If you're diving with a non-long hose diver, make sure you go over OOA situations in the pre-dive. Make sure they understand that YOU will be GIVING them the regulator out of your mouth.
If you're diving with a DIR team, everyone should know not to reach for anyone's reg out of their mouths. Signal and people will donate. Remember donate means YOU give.
Rescue classes actually recommend that you stay out of reach of a panicked diver. Which implies that you're responsible for giving the panicked diver your octo. As opposed to OW training where the OOA diver is taught to reach for the octo. They should stick to one concept.
Avoiding "targets" is a good idea, but the yellow cover isn't a problem. You should be able to get a different colored cover from an authorized reseller. On the backup, point the cover down. This allows you to drop your head and grab the backup with your mouth. But depending on reg, you may experience freeflow.
Sorry to hammer on the air-sharing, but it seems to be one of those gray areas.
Ken
PS - O-ring is just screwing around... I witnessed him drift scooter deco-ing with a CCR on his back... solo I might add.