APC switched rack PDU: Startup outlet state

You don't specify what kind of environment you work in and what the systems are used for, but I'll make some general statements. Given that you use an ADSL connection, I'm going to assume you're not hosting any world-facing applications (websites, email, etc.)

During the power outage, there's not a whole lot you can do. If you're running off a generator (doesn't sound like it) or a shared UPS, shut down development systems as early as possible -- it'll leave more power for your production systems.

The key is in the planning -- when you say "last possible minute," what if your systems take slightly longer to shut down than usual? Are you risking data by an improper shutdown? I would leave more padding.

Where I work, none of our systems shut down during an outage -- we have a room-wide UPS that's backed by a natural gas generator, so we hope everything stays up for an outage of almost any length.

Multiple PSUs in servers are ok but not a magic bullet. Often when things to do with power go they take out other things around them eg. the backplane that your redundant psus both connect to. Far more likely to keep running if you have two servers on seperate UPSs.

Best of all is to work in redundancy at your application or platform layer so that machines or racks can go out without it causing a problem but when you haven't got the budget for that you can still reduce the risk by having spares of any non redundant equipment ready to swap out, but also by keeping things simple. A fancy managed PDU is far more likely to go down than a dumb power bar.

Also it is worth bearing in mind that many small businesses simply can't do things the proper way or choose to do things the cheapest way and live with the consequences if they happen. I've seen inexperienced admins go out of their way to avoid doing things a certain way that have been slated around here or similar sites only to put something worse in place. A less than ideal solution is often better than nothing.