+A: No.
+
+When swsusp was created, ACPI was not too widespread, so we tried to
+avoid using ACPI-specific stuff. ACPI also is/was notoriously
+buggy. These days swsusp works on APM-only i386 machines and even
+without any power managment at all. Some versions also work on PPC.
+
+That means that machine does not enter S4 on suspend-to-disk, but
+simply enters S5. That has few advantages, you can for example boot
+windows on next boot, and return to your Linux session later. You
+could even have few different Linuxes on your box (not sharing any
+partitions), and switch between them.
+
+It also has disadvantages. On HP nx5000, if you unplug power cord
+while machine is suspended-to-disk, Linux will fail to notice that.