you dive it disconnected with the LP hose bungeed to the inflator. haven't seen one magically self-connect, and takes seconds to connect and be back on track. no downside, as I have yet to see one connect itself on a dive.
yes, a drysuit is a great form of redundant buoyancy, if you also need it for thermal protection. otherwise, you're adding several failure points on top of the dump and LP inflator. I've seen way more dives called due to blown DS seals than failed backup inflators. In an environment where the air temp is 90+, and the water temp is 86 all the way to the bottom, a drysuit can be horribly uncomfortable.
the argument can go on for days, the important thing is you need to have some sort of a plan in the event of BC loss. whether it's a balanced rig that you can swim up, drysuit, lift bag, or truly redundant wing, it needs to be appropriate for the environment you are diving in and you need to be proficient in its use.
yes, PADI has a standard for everything, and they do require either a drysuit or dual bladder wing for redundant bouyancy.